src/auth/password-scheme.c

	password-scheme.c revision 8e0265f999e2fb4be4add5437df12f780a89b44e
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen/* Copyright (c) 2003-2011 Dovecot authors, see the included COPYING file */
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen#include "lib.h"
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen#include "array.h"
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen#include "base64.h"
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen#include "hex-binary.h"
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen#include "md4.h"
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen#include "md5.h"
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen#include "hmac-md5.h"
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen#include "ntlm.h"
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen#include "mycrypt.h"
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen#include "randgen.h"
202a34580f6204672d9b0d6a0756f35a3c4cdef6Timo Sirainen#include "sha1.h"
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen#include "sha2.h"
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen#include "otp.h"
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen#include "str.h"
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen#include "password-scheme.h"
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainenstatic const char salt_chars[] =
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen    "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen
202a34580f6204672d9b0d6a0756f35a3c4cdef6Timo SirainenARRAY_TYPE(password_scheme_p) password_schemes;
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainenstatic const struct password_scheme *
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainenpassword_scheme_lookup_name(const char *name)
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen{
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen    const struct password_scheme *const *schemes;
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen    array_foreach(&password_schemes, schemes) {
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen        const struct password_scheme *scheme = *schemes;
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen
202a34580f6204672d9b0d6a0756f35a3c4cdef6Timo Sirainen        if (strcasecmp(scheme->name, name) == 0)
202a34580f6204672d9b0d6a0756f35a3c4cdef6Timo Sirainen            return scheme;
202a34580f6204672d9b0d6a0756f35a3c4cdef6Timo Sirainen    }
202a34580f6204672d9b0d6a0756f35a3c4cdef6Timo Sirainen    return NULL;
202a34580f6204672d9b0d6a0756f35a3c4cdef6Timo Sirainen}
202a34580f6204672d9b0d6a0756f35a3c4cdef6Timo Sirainen
202a34580f6204672d9b0d6a0756f35a3c4cdef6Timo Sirainen/* Lookup scheme and encoding by given name. The encoding is taken from
202a34580f6204672d9b0d6a0756f35a3c4cdef6Timo Sirainen   ".base64", ".b64" or ".hex" suffix if it exists, otherwise the default
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen   encoding is used. */
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainenstatic const struct password_scheme *
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainenpassword_scheme_lookup(const char *name, enum password_encoding *encoding_r)
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen{
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen    const struct password_scheme *scheme;
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen    const char *encoding = NULL;
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen    unsigned int scheme_len;
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen    *encoding_r = PW_ENCODING_NONE;
cbb79ea1b1a49255c6edc46409a544666b22788fTimo Sirainen
cbb79ea1b1a49255c6edc46409a544666b22788fTimo Sirainen    for (scheme_len = 0; name[scheme_len] != '\0'; scheme_len++) {
cbb79ea1b1a49255c6edc46409a544666b22788fTimo Sirainen        if (name[scheme_len] == '.') {
cbb79ea1b1a49255c6edc46409a544666b22788fTimo Sirainen            encoding = name + scheme_len + 1;
cbb79ea1b1a49255c6edc46409a544666b22788fTimo Sirainen            name = t_strndup(name, scheme_len);
cbb79ea1b1a49255c6edc46409a544666b22788fTimo Sirainen            break;
cbb79ea1b1a49255c6edc46409a544666b22788fTimo Sirainen        }
1c6f6f5bef70f16546b3bc8f4cd5f93f373e82a2Timo Sirainen    }
1c6f6f5bef70f16546b3bc8f4cd5f93f373e82a2Timo Sirainen
cbb79ea1b1a49255c6edc46409a544666b22788fTimo Sirainen    scheme = password_scheme_lookup_name(name);
cbb79ea1b1a49255c6edc46409a544666b22788fTimo Sirainen    if (scheme == NULL)
cbb79ea1b1a49255c6edc46409a544666b22788fTimo Sirainen        return NULL;
cbb79ea1b1a49255c6edc46409a544666b22788fTimo Sirainen
cbb79ea1b1a49255c6edc46409a544666b22788fTimo Sirainen    if (encoding == NULL)
cbb79ea1b1a49255c6edc46409a544666b22788fTimo Sirainen        *encoding_r = scheme->default_encoding;
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen    else if (strcasecmp(encoding, "b64") == 0 ||
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen         strcasecmp(encoding, "base64") == 0)
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen        *encoding_r = PW_ENCODING_BASE64;
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen    else if (strcasecmp(encoding, "hex") == 0)
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen        *encoding_r = PW_ENCODING_HEX;
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen    else {
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen        /* unknown encoding. treat as invalid scheme. */
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen        return NULL;
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen    }
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen    return scheme;
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen}
cbb79ea1b1a49255c6edc46409a544666b22788fTimo Sirainen
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainenint password_verify(const char *plaintext, const char *user, const char *scheme,
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen            const unsigned char *raw_password, size_t size,
cbb79ea1b1a49255c6edc46409a544666b22788fTimo Sirainen            const char **error_r)
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen{
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen    const struct password_scheme *s;
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen    enum password_encoding encoding;
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen    const unsigned char *generated;
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen    size_t generated_size;
3157f61431f19e01173e2e0d270c28af86dc97aaTimo Sirainen
    s = password_scheme_lookup(scheme, &encoding);
    if (s == NULL) {
        *error_r = "Unknown password scheme";
        return -1;
    }

    if (s->password_verify != NULL) {
        return s->password_verify(plaintext, user, raw_password, size,
                      error_r);
    }

    /* generic verification handler: generate the password and compare it
       to the one in database */
    s->password_generate(plaintext, user, &generated, &generated_size);
    return size != generated_size ? 0 :
        memcmp(generated, raw_password, size) == 0 ? 1 : 0;
}

const char *password_get_scheme(const char **password)
{
    const char *p, *scheme;

    if (*password == NULL)
        return NULL;

    if (strncmp(*password, "$1$", 3) == 0) {
        /* $1$<salt>$<password>[$<ignored>] */
        p = strchr(*password + 3, '$');
        if (p != NULL) {
            /* stop at next '$' after password */
            p = strchr(p+1, '$');
            if (p != NULL)
                *password = t_strdup_until(*password, p);
            return "MD5-CRYPT";
        }
    }

    if (**password != '{')
        return NULL;

    p = strchr(*password, '}');
    if (p == NULL)
        return NULL;

    scheme = t_strdup_until(*password + 1, p);
    *password = p + 1;
    return scheme;
}

int password_decode(const char *password, const char *scheme,
            const unsigned char **raw_password_r, size_t *size_r,
            const char **error_r)
{
    const struct password_scheme *s;
    enum password_encoding encoding;
    buffer_t *buf;
    unsigned int len;
    bool guessed_encoding;

    *error_r = NULL;

    s = password_scheme_lookup(scheme, &encoding);
    if (s == NULL) {
        *error_r = "Unknown scheme";
        return 0;
    }

    len = strlen(password);
    if (encoding != PW_ENCODING_NONE && s->raw_password_len != 0 &&
        strchr(scheme, '.') == NULL) {
        /* encoding not specified. we can guess quite well between
           base64 and hex encodings. the only problem is distinguishing
           2 character strings, but there shouldn't be any that short
           raw_password_lens. */
        encoding = len == s->raw_password_len * 2 ?
            PW_ENCODING_HEX : PW_ENCODING_BASE64;
        guessed_encoding = TRUE;
    } else {
        guessed_encoding = FALSE;
    }

    switch (encoding) {
    case PW_ENCODING_NONE:
        *raw_password_r = (const unsigned char *)password;
        *size_r = len;
        break;
    case PW_ENCODING_HEX:
        buf = buffer_create_dynamic(pool_datastack_create(),
                        len / 2 + 1);
        if (hex_to_binary(password, buf) == 0) {
            *raw_password_r = buf->data;
            *size_r = buf->used;
            break;
        }
        if (!guessed_encoding) {
            *error_r = "Input isn't valid HEX encoded data";
            return -1;
        }
        /* fall through, just in case it was base64-encoded after
           all. some input lengths produce matching hex and base64
           encoded lengths. */
    case PW_ENCODING_BASE64:
        buf = buffer_create_dynamic(pool_datastack_create(),
                        MAX_BASE64_DECODED_SIZE(len));
        if (base64_decode(password, len, NULL, buf) < 0) {
            *error_r = "Input isn't valid base64 encoded data";
            return -1;
        }

        *raw_password_r = buf->data;
        *size_r = buf->used;
        break;
    }
    if (s->raw_password_len != *size_r && s->raw_password_len != 0) {
        /* password has invalid length */
        *error_r = t_strdup_printf(
            "Input length isn't valid (%u instead of %u)",
            (unsigned int)*size_r, s->raw_password_len);
        return -1;
    }
    return 1;
}

bool password_generate(const char *plaintext, const char *user,
               const char *scheme,
               const unsigned char **raw_password_r, size_t *size_r)
{
    const struct password_scheme *s;
    enum password_encoding encoding;

    s = password_scheme_lookup(scheme, &encoding);
    if (s == NULL)
        return FALSE;

    s->password_generate(plaintext, user, raw_password_r, size_r);
    return TRUE;
}

bool password_generate_encoded(const char *plaintext, const char *user,
                   const char *scheme, const char **password_r)
{
    const struct password_scheme *s;
    const unsigned char *raw_password;
    enum password_encoding encoding;
    string_t *str;
    size_t size;

    s = password_scheme_lookup(scheme, &encoding);
    if (s == NULL)
        return FALSE;

    s->password_generate(plaintext, user, &raw_password, &size);
    switch (encoding) {
    case PW_ENCODING_NONE:
        *password_r = t_strndup(raw_password, size);
        break;
    case PW_ENCODING_BASE64:
        str = t_str_new(MAX_BASE64_ENCODED_SIZE(size) + 1);
        base64_encode(raw_password, size, str);
        *password_r = str_c(str);
        break;
    case PW_ENCODING_HEX:
        *password_r = binary_to_hex(raw_password, size);
        break;
    }
    return TRUE;
}

const char *password_generate_salt(size_t len)
{
    unsigned int i;
    char *salt;

    salt = t_malloc(len + 1);
    random_fill(salt, len);
    for (i = 0; i < len; i++)
        salt[i] = salt_chars[salt[i] % (sizeof(salt_chars)-1)];
    salt[len] = '\0';
    return salt;
}

bool password_scheme_is_alias(const char *scheme1, const char *scheme2)
{
    const struct password_scheme *const *schemes, *s1 = NULL, *s2 = NULL;

    scheme1 = t_strcut(scheme1, '.');
    scheme2 = t_strcut(scheme2, '.');

    if (strcasecmp(scheme1, scheme2) == 0)
        return TRUE;

    array_foreach(&password_schemes, schemes) {
        const struct password_scheme *scheme = *schemes;

        if (strcasecmp(scheme->name, scheme1) == 0)
            s1 = scheme;
        else if (strcasecmp(scheme->name, scheme2) == 0)
            s2 = scheme;
    }

    /* if they've the same generate function, they're equivalent */
    return s1 != NULL && s2 != NULL &&
        s1->password_generate == s2->password_generate;
}

const char *
password_scheme_detect(const char *plain_password, const char *crypted_password,
               const char *user)
{
    const struct password_scheme *const *schemes;
    unsigned int i, count;
    const unsigned char *raw_password;
    size_t raw_password_size;
    const char *error;

    schemes = array_get(&password_schemes, &count);
    for (i = 0; i < count; i++) {
        if (password_decode(crypted_password, schemes[i]->name,
                    &raw_password, &raw_password_size,
                    &error) <= 0)
            continue;

        if (password_verify(plain_password, user, schemes[i]->name,
                    raw_password, raw_password_size,
                    &error) > 0)
            return schemes[i]->name;
    }
    return NULL;
}

int crypt_verify(const char *plaintext, const char *user ATTR_UNUSED,
         const unsigned char *raw_password, size_t size,
         const char **error_r)
{
    const char *password, *crypted;

    if (size == 0) {
        /* the default mycrypt() handler would return match */
        return 0;
    }

    password = t_strndup(raw_password, size);
    crypted = mycrypt(plaintext, password);
    if (crypted == NULL) {
        /* really shouldn't happen unless the system is broken */
        *error_r = t_strdup_printf("crypt() failed: %m");
        return -1;
    }

    return strcmp(crypted, password) == 0 ? 1 : 0;
}

static void
crypt_generate(const char *plaintext, const char *user ATTR_UNUSED,
           const unsigned char **raw_password_r, size_t *size_r)
{
#define CRYPT_SALT_LEN 2
    const char *password, *salt;

    salt = password_generate_salt(CRYPT_SALT_LEN);
    password = t_strdup(mycrypt(plaintext, salt));
    *raw_password_r = (const unsigned char *)password;
    *size_r = strlen(password);
}

static int
md5_verify(const char *plaintext, const char *user,
       const unsigned char *raw_password, size_t size, const char **error_r)
{
    const char *password, *str, *error;
    const unsigned char *md5_password;
    size_t md5_size;

    password = t_strndup(raw_password, size);
    if (strncmp(password, "$1$", 3) == 0) {
        /* MD5-CRYPT */
        str = password_generate_md5_crypt(plaintext, password);
        return strcmp(str, password) == 0 ? 1 : 0;
    } else if (password_decode(password, "PLAIN-MD5",
                   &md5_password, &md5_size, &error) < 0) {
        *error_r = "Not a valid MD5-CRYPT or PLAIN-MD5 password";
        return -1;
    } else {
        return password_verify(plaintext, user, "PLAIN-MD5",
                       md5_password, md5_size, error_r);
    }
}

static int
md5_crypt_verify(const char *plaintext, const char *user ATTR_UNUSED,
         const unsigned char *raw_password, size_t size,
         const char **error_r ATTR_UNUSED)
{
    const char *password, *str;

    password = t_strndup(raw_password, size);
    str = password_generate_md5_crypt(plaintext, password);
    return strcmp(str, password) == 0 ? 1 : 0;
}

static void
md5_crypt_generate(const char *plaintext, const char *user ATTR_UNUSED,
           const unsigned char **raw_password_r, size_t *size_r)
{
    const char *password;
    char salt[9];
    unsigned int i;

    random_fill(salt, sizeof(salt)-1);
    for (i = 0; i < sizeof(salt)-1; i++)
        salt[i] = salt_chars[salt[i] % (sizeof(salt_chars)-1)];
    salt[sizeof(salt)-1] = '\0';

    password = password_generate_md5_crypt(plaintext, salt);
    *raw_password_r = (const unsigned char *)password;
    *size_r = strlen(password);
}

static void
sha1_generate(const char *plaintext, const char *user ATTR_UNUSED,
          const unsigned char **raw_password_r, size_t *size_r)
{
    unsigned char *digest;

    digest = t_malloc(SHA1_RESULTLEN);
    sha1_get_digest(plaintext, strlen(plaintext), digest);

    *raw_password_r = digest;
    *size_r = SHA1_RESULTLEN;
}

static void
sha256_generate(const char *plaintext, const char *user ATTR_UNUSED,
        const unsigned char **raw_password_r, size_t *size_r)
{
    unsigned char *digest;

    digest = t_malloc(SHA256_RESULTLEN);
    sha256_get_digest(plaintext, strlen(plaintext), digest);

    *raw_password_r = digest;
    *size_r = SHA256_RESULTLEN;
}

static void
sha512_generate(const char *plaintext, const char *user ATTR_UNUSED,
        const unsigned char **raw_password_r, size_t *size_r)
{
    unsigned char *digest;

    digest = t_malloc(SHA512_RESULTLEN);
    sha512_get_digest(plaintext, strlen(plaintext), digest);

    *raw_password_r = digest;
    *size_r = SHA512_RESULTLEN;
}

static void
ssha_generate(const char *plaintext, const char *user ATTR_UNUSED,
          const unsigned char **raw_password_r, size_t *size_r)
{
#define SSHA_SALT_LEN 4
    unsigned char *digest, *salt;
    struct sha1_ctxt ctx;

    digest = t_malloc(SHA1_RESULTLEN + SSHA_SALT_LEN);
    salt = digest + SHA1_RESULTLEN;
    random_fill(salt, SSHA_SALT_LEN);

    sha1_init(&ctx);
    sha1_loop(&ctx, plaintext, strlen(plaintext));
    sha1_loop(&ctx, salt, SSHA_SALT_LEN);
    sha1_result(&ctx, digest);

    *raw_password_r = digest;
    *size_r = SHA1_RESULTLEN + SSHA_SALT_LEN;
}

static int ssha_verify(const char *plaintext, const char *user ATTR_UNUSED,
               const unsigned char *raw_password, size_t size,
               const char **error_r)
{
    unsigned char sha1_digest[SHA1_RESULTLEN];
    struct sha1_ctxt ctx;

    /* format: <SHA1 hash><salt> */
    if (size <= SHA1_RESULTLEN) {
        *error_r = "SSHA password is too short";
        return -1;
    }

    sha1_init(&ctx);
    sha1_loop(&ctx, plaintext, strlen(plaintext));
    sha1_loop(&ctx, raw_password + SHA1_RESULTLEN, size - SHA1_RESULTLEN);
    sha1_result(&ctx, sha1_digest);
    return memcmp(sha1_digest, raw_password, SHA1_RESULTLEN) == 0 ? 1 : 0;
}

static void
ssha256_generate(const char *plaintext, const char *user ATTR_UNUSED,
         const unsigned char **raw_password_r, size_t *size_r)
{
#define SSHA256_SALT_LEN 4
    unsigned char *digest, *salt;
    struct sha256_ctx ctx;

    digest = t_malloc(SHA256_RESULTLEN + SSHA256_SALT_LEN);
    salt = digest + SHA256_RESULTLEN;
    random_fill(salt, SSHA256_SALT_LEN);

    sha256_init(&ctx);
    sha256_loop(&ctx, plaintext, strlen(plaintext));
    sha256_loop(&ctx, salt, SSHA256_SALT_LEN);
    sha256_result(&ctx, digest);

    *raw_password_r = digest;
    *size_r = SHA256_RESULTLEN + SSHA256_SALT_LEN;
}

static int ssha256_verify(const char *plaintext, const char *user ATTR_UNUSED,
              const unsigned char *raw_password, size_t size,
              const char **error_r)
{
    unsigned char sha256_digest[SHA256_RESULTLEN];
    struct sha256_ctx ctx;

    /* format: <SHA256 hash><salt> */
    if (size <= SHA256_RESULTLEN) {
        *error_r = "SSHA256 password is too short";
        return -1;
    }

    sha256_init(&ctx);
    sha256_loop(&ctx, plaintext, strlen(plaintext));
    sha256_loop(&ctx, raw_password + SHA256_RESULTLEN,
            size - SHA256_RESULTLEN);
    sha256_result(&ctx, sha256_digest);
    return memcmp(sha256_digest, raw_password,
              SHA256_RESULTLEN) == 0 ? 1 : 0;
}

static void
ssha512_generate(const char *plaintext, const char *user ATTR_UNUSED,
         const unsigned char **raw_password_r, size_t *size_r)
{
#define SSHA512_SALT_LEN 4
    unsigned char *digest, *salt;
    struct sha512_ctx ctx;

    digest = t_malloc(SHA512_RESULTLEN + SSHA512_SALT_LEN);
    salt = digest + SHA512_RESULTLEN;
    random_fill(salt, SSHA512_SALT_LEN);

    sha512_init(&ctx);
    sha512_loop(&ctx, plaintext, strlen(plaintext));
    sha512_loop(&ctx, salt, SSHA512_SALT_LEN);
    sha512_result(&ctx, digest);

    *raw_password_r = digest;
    *size_r = SHA512_RESULTLEN + SSHA512_SALT_LEN;
}

static int ssha512_verify(const char *plaintext, const char *user ATTR_UNUSED,
              const unsigned char *raw_password, size_t size,
              const char **error_r)
{
    unsigned char sha512_digest[SHA512_RESULTLEN];
    struct sha512_ctx ctx;

    /* format: <SHA512 hash><salt> */
    if (size <= SHA512_RESULTLEN) {
        *error_r = "SSHA512 password is too short";
        return -1;
    }

    sha512_init(&ctx);
    sha512_loop(&ctx, plaintext, strlen(plaintext));
    sha512_loop(&ctx, raw_password + SHA512_RESULTLEN,
            size - SHA512_RESULTLEN);
    sha512_result(&ctx, sha512_digest);
    return memcmp(sha512_digest, raw_password,
              SHA512_RESULTLEN) == 0 ? 1 : 0;
}

static void
smd5_generate(const char *plaintext, const char *user ATTR_UNUSED,
          const unsigned char **raw_password_r, size_t *size_r)
{
#define SMD5_SALT_LEN 4
    unsigned char *digest, *salt;
    struct md5_context ctx;

    digest = t_malloc(MD5_RESULTLEN + SMD5_SALT_LEN);
    salt = digest + MD5_RESULTLEN;
    random_fill(salt, SMD5_SALT_LEN);

    md5_init(&ctx);
    md5_update(&ctx, plaintext, strlen(plaintext));
    md5_update(&ctx, salt, SMD5_SALT_LEN);
    md5_final(&ctx, digest);

    *raw_password_r = digest;
    *size_r = MD5_RESULTLEN + SMD5_SALT_LEN;
}

static int smd5_verify(const char *plaintext, const char *user ATTR_UNUSED,
               const unsigned char *raw_password, size_t size,
               const char **error_r)
{
    unsigned char md5_digest[MD5_RESULTLEN];
    struct md5_context ctx;

    /* format: <MD5 hash><salt> */
    if (size <= MD5_RESULTLEN) {
        *error_r = "SMD5 password is too short";
        return -1;
    }

    md5_init(&ctx);
    md5_update(&ctx, plaintext, strlen(plaintext));
    md5_update(&ctx, raw_password + MD5_RESULTLEN, size - MD5_RESULTLEN);
    md5_final(&ctx, md5_digest);
    return memcmp(md5_digest, raw_password, MD5_RESULTLEN) == 0 ? 1 : 0;
}

static void
plain_generate(const char *plaintext, const char *user ATTR_UNUSED,
           const unsigned char **raw_password_r, size_t *size_r)
{
    *raw_password_r = (const unsigned char *)plaintext,
    *size_r = strlen(plaintext);
}

static int
plain_trunc_verify(const char *plaintext, const char *user ATTR_UNUSED,
           const unsigned char *raw_password, size_t size,
           const char **error_r)
{
    unsigned int i, plaintext_len, trunc_len = 0;

    /* format: <length>-<password> */
    for (i = 0; i < size; i++) {
        if (raw_password[i] >= '0' && raw_password[i] <= '9')
            trunc_len = trunc_len*10 + raw_password[i]-'0';
        else
            break;
    }
    if (i == size || raw_password[i] != '-') {
        *error_r = "PLAIN-TRUNC missing length: prefix";
        return -1;
    }
    i++;

    plaintext_len = strlen(plaintext);
    if (size-i == trunc_len && plaintext_len >= trunc_len) {
        /* possibly truncated password. allow the given password as
           long as the prefix matches. */
        return memcmp(raw_password+i, plaintext, trunc_len) == 0 ? 1 : 0;
    }
    return plaintext_len == size-i &&
        memcmp(raw_password+i, plaintext, plaintext_len) == 0 ? 1 : 0;
}

static void
cram_md5_generate(const char *plaintext, const char *user ATTR_UNUSED,
          const unsigned char **raw_password_r, size_t *size_r)
{
    struct hmac_md5_context ctx;
    unsigned char *context_digest;

    context_digest = t_malloc(CRAM_MD5_CONTEXTLEN);
    hmac_md5_init(&ctx, (const unsigned char *)plaintext,
              strlen(plaintext));
    hmac_md5_get_cram_context(&ctx, context_digest);

    *raw_password_r = context_digest;
    *size_r = CRAM_MD5_CONTEXTLEN;
}

static void
digest_md5_generate(const char *plaintext, const char *user,
            const unsigned char **raw_password_r, size_t *size_r)
{
    const char *realm, *str;
    unsigned char *digest;

    if (user == NULL)
        i_fatal("digest_md5_generate(): username not given");


    /* assume user@realm format for username. If user@domain is wanted
       in the username, allow also user@domain@realm. */
    realm = strrchr(user, '@');
    if (realm != NULL) {
        user = t_strdup_until(user, realm);
        realm++;
    } else {
        realm = "";
    }

    /* user:realm:passwd */
    digest = t_malloc(MD5_RESULTLEN);
    str = t_strdup_printf("%s:%s:%s", user, realm, plaintext);
    md5_get_digest(str, strlen(str), digest);

    *raw_password_r = digest;
    *size_r = MD5_RESULTLEN;
}

static void
plain_md4_generate(const char *plaintext, const char *user ATTR_UNUSED,
           const unsigned char **raw_password_r, size_t *size_r)
{
    unsigned char *digest;

    digest = t_malloc(MD4_RESULTLEN);
    md4_get_digest(plaintext, strlen(plaintext), digest);

    *raw_password_r = digest;
    *size_r = MD4_RESULTLEN;
}

static void
plain_md5_generate(const char *plaintext, const char *user ATTR_UNUSED,
           const unsigned char **raw_password_r, size_t *size_r)
{
    unsigned char *digest;

    digest = t_malloc(MD5_RESULTLEN);
    md5_get_digest(plaintext, strlen(plaintext), digest);

    *raw_password_r = digest;
    *size_r = MD5_RESULTLEN;
}

static void
lm_generate(const char *plaintext, const char *user ATTR_UNUSED,
        const unsigned char **raw_password_r, size_t *size_r)
{
    unsigned char *digest;

    digest = t_malloc(LM_HASH_SIZE);
    lm_hash(plaintext, digest);

    *raw_password_r = digest;
    *size_r = LM_HASH_SIZE;
}

static void
ntlm_generate(const char *plaintext, const char *user ATTR_UNUSED,
          const unsigned char **raw_password_r, size_t *size_r)
{
    unsigned char *digest;

    digest = t_malloc(NTLMSSP_HASH_SIZE);
    ntlm_v1_hash(plaintext, digest);

    *raw_password_r = digest;
    *size_r = NTLMSSP_HASH_SIZE;
}

static int otp_verify(const char *plaintext, const char *user ATTR_UNUSED,
              const unsigned char *raw_password, size_t size,
              const char **error_r)
{
    const char *password, *generated;

    password = t_strndup(raw_password, size);
    if (password_generate_otp(plaintext, password, -1, &generated) < 0) {
        *error_r = "Invalid OTP data in passdb";
        return -1;
    }

    return strcasecmp(password, generated) == 0 ? 1 : 0;
}

static void
otp_generate(const char *plaintext, const char *user ATTR_UNUSED,
         const unsigned char **raw_password_r, size_t *size_r)
{
    const char *password;

    if (password_generate_otp(plaintext, NULL, OTP_HASH_SHA1, &password) < 0)
        i_unreached();
    *raw_password_r = (const unsigned char *)password;
    *size_r = strlen(password);
}

static void
skey_generate(const char *plaintext, const char *user ATTR_UNUSED,
          const unsigned char **raw_password_r, size_t *size_r)
{
    const char *password;

    if (password_generate_otp(plaintext, NULL, OTP_HASH_MD4, &password) < 0)
        i_unreached();
    *raw_password_r = (const unsigned char *)password;
    *size_r = strlen(password);
}

static void
rpa_generate(const char *plaintext, const char *user ATTR_UNUSED,
         const unsigned char **raw_password_r, size_t *size_r)
{
    unsigned char *digest;

    digest = t_malloc(MD5_RESULTLEN);
    password_generate_rpa(plaintext, digest);

    *raw_password_r = digest;
    *size_r = MD5_RESULTLEN;
}

static const struct password_scheme builtin_schemes[] = {
    { "CRYPT", PW_ENCODING_NONE, 0, crypt_verify, crypt_generate },
    { "MD5", PW_ENCODING_NONE, 0, md5_verify, md5_crypt_generate },
    { "MD5-CRYPT", PW_ENCODING_NONE, 0,
      md5_crypt_verify, md5_crypt_generate },
    { "SHA", PW_ENCODING_BASE64, SHA1_RESULTLEN, NULL, sha1_generate },
    { "SHA1", PW_ENCODING_BASE64, SHA1_RESULTLEN, NULL, sha1_generate },
    { "SHA256", PW_ENCODING_BASE64, SHA256_RESULTLEN,
      NULL, sha256_generate },
    { "SHA512", PW_ENCODING_BASE64, SHA512_RESULTLEN,
      NULL, sha512_generate },
    { "SMD5", PW_ENCODING_BASE64, 0, smd5_verify, smd5_generate },
    { "SSHA", PW_ENCODING_BASE64, 0, ssha_verify, ssha_generate },
    { "SSHA256", PW_ENCODING_BASE64, 0, ssha256_verify, ssha256_generate },
    { "SSHA512", PW_ENCODING_BASE64, 0, ssha512_verify, ssha512_generate },
    { "PLAIN", PW_ENCODING_NONE, 0, NULL, plain_generate },
    { "CLEARTEXT", PW_ENCODING_NONE, 0, NULL, plain_generate },
    { "PLAIN-TRUNC", PW_ENCODING_NONE, 0, plain_trunc_verify, plain_generate },
    { "CRAM-MD5", PW_ENCODING_HEX, CRAM_MD5_CONTEXTLEN,
      NULL, cram_md5_generate },
    { "HMAC-MD5", PW_ENCODING_HEX, CRAM_MD5_CONTEXTLEN,
      NULL, cram_md5_generate },
    { "DIGEST-MD5", PW_ENCODING_HEX, MD5_RESULTLEN,
      NULL, digest_md5_generate },
    { "PLAIN-MD4", PW_ENCODING_HEX, MD4_RESULTLEN,
      NULL, plain_md4_generate },
    { "PLAIN-MD5", PW_ENCODING_HEX, MD5_RESULTLEN,
      NULL, plain_md5_generate },
    { "LDAP-MD5", PW_ENCODING_BASE64, MD5_RESULTLEN,
      NULL, plain_md5_generate },
    { "LANMAN", PW_ENCODING_HEX, LM_HASH_SIZE, NULL, lm_generate },
    { "NTLM", PW_ENCODING_HEX, NTLMSSP_HASH_SIZE, NULL, ntlm_generate },
    { "OTP", PW_ENCODING_NONE, 0, otp_verify, otp_generate },
    { "SKEY", PW_ENCODING_NONE, 0, otp_verify, skey_generate },
    { "RPA", PW_ENCODING_HEX, MD5_RESULTLEN, NULL, rpa_generate }
};

void password_scheme_register(const struct password_scheme *scheme)
{
    if (password_scheme_lookup_name(scheme->name) != NULL) {
        i_panic("password_scheme_register(%s): Already registered",
            scheme->name);
    }
    array_append(&password_schemes, &scheme, 1);
}

void password_scheme_unregister(const struct password_scheme *scheme)
{
    const struct password_scheme *const *schemes;
    unsigned int idx;

    array_foreach(&password_schemes, schemes) {
        if (strcasecmp((*schemes)->name, scheme->name) == 0) {
            idx = array_foreach_idx(&password_schemes, schemes);
            array_delete(&password_schemes, idx, 1);
            return;
        }
    }
    i_panic("password_scheme_unregister(%s): Not registered", scheme->name);
}

void password_schemes_init(void)
{
    unsigned int i;

    i_array_init(&password_schemes, N_ELEMENTS(builtin_schemes) + 4);
    for (i = 0; i < N_ELEMENTS(builtin_schemes); i++)
        password_scheme_register(&builtin_schemes[i]);
    password_scheme_register_crypt();
}

void password_schemes_deinit(void)
{
    array_free(&password_schemes);
}