/*

 * Copyright 1995-2021 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the Apache License 2.0 (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

/*

 * RSA low level APIs are deprecated for public use, but still ok for

 * internal use.

 */

#include "internal/deprecated.h"

#include <stdio.h>

#include "internal/cryptlib.h"

#include <openssl/bn.h>

#include <openssl/rsa.h>

#include <openssl/objects.h>

#ifndef FIPS_MODULE

#ifndef OPENSSL_NO_MD2

#include <openssl/md2.h> /* uses MD2_DIGEST_LENGTH */

#endif

#ifndef OPENSSL_NO_MD4

#include <openssl/md4.h> /* uses MD4_DIGEST_LENGTH */

#endif

#ifndef OPENSSL_NO_MD5

#include <openssl/md5.h> /* uses MD5_DIGEST_LENGTH */

#endif

#ifndef OPENSSL_NO_MDC2

#include <openssl/mdc2.h> /* uses MDC2_DIGEST_LENGTH */

#endif

#ifndef OPENSSL_NO_RMD160

#include <openssl/ripemd.h> /* uses RIPEMD160_DIGEST_LENGTH */

#endif

#endif

#include <openssl/sha.h> /* uses SHA???_DIGEST_LENGTH */

#include "crypto/rsa.h"

#include "rsa_local.h"

/*

 * The general purpose ASN1 code is not available inside the FIPS provider.

 * To remove the dependency RSASSA-PKCS1-v1_5 DigestInfo encodings can be

 * treated as a special case by pregenerating the required ASN1 encoding.

 * This encoding will also be shared by the default provider.

 *

 * The EMSA-PKCS1-v1_5 encoding method includes an ASN.1 value of type

 * DigestInfo, where the type DigestInfo has the syntax

 *

 *     DigestInfo ::= SEQUENCE {

 *         digestAlgorithm DigestAlgorithm,

 *         digest OCTET STRING

 *     }

 *

 *     DigestAlgorithm ::= AlgorithmIdentifier {

 *         {PKCS1-v1-5DigestAlgorithms}

 *     }

 *

 * The AlgorithmIdentifier is a sequence containing the digest OID and

 * parameters (a value of type NULL).

 *

 * The ENCODE_DIGESTINFO_SHA() and ENCODE_DIGESTINFO_MD() macros define an

 * initialized array containing the DER encoded DigestInfo for the specified

 * SHA or MD digest. The content of the OCTET STRING is not included.

 * |name| is the digest name.

 * |n| is last byte in the encoded OID for the digest.

 * |sz| is the digest length in bytes. It must not be greater than 110.

 */

#define ASN1_SEQUENCE 0x30

#define ASN1_OCTET_STRING 0x04

#define ASN1_NULL 0x05

#define ASN1_OID 0x06

/* SHA OIDs are of the form: (2 16 840 1 101 3 4 2 |n|) */

#define ENCODE_DIGESTINFO_SHA(name, n, sz)                           \

    static const unsigned char digestinfo_##name##_der[] = {         \

        ASN1_SEQUENCE, 0x11 + sz,                                    \

        ASN1_SEQUENCE, 0x0d,                                         \

        ASN1_OID, 0x09, 2 * 40 + 16, 0x86, 0x48, 1, 101, 3, 4, 2, n, \

        ASN1_NULL, 0x00,                                             \

        ASN1_OCTET_STRING, sz                                        \

    };

/* MD2, MD4 and MD5 OIDs are of the form: (1 2 840 113549 2 |n|) */

#define ENCODE_DIGESTINFO_MD(name, n, sz)                               \

    static const unsigned char digestinfo_##name##_der[] = {            \

        ASN1_SEQUENCE, 0x10 + sz,                                       \

        ASN1_SEQUENCE, 0x0c,                                            \

        ASN1_OID, 0x08, 1 * 40 + 2, 0x86, 0x48, 0x86, 0xf7, 0x0d, 2, n, \

        ASN1_NULL, 0x00,                                                \

        ASN1_OCTET_STRING, sz                                           \

    };

#ifndef FIPS_MODULE

#ifndef OPENSSL_NO_MD2

ENCODE_DIGESTINFO_MD(md2, 0x02, MD2_DIGEST_LENGTH)

#endif

#ifndef OPENSSL_NO_MD4

ENCODE_DIGESTINFO_MD(md4, 0x03, MD4_DIGEST_LENGTH)

#endif

#ifndef OPENSSL_NO_MD5

ENCODE_DIGESTINFO_MD(md5, 0x05, MD5_DIGEST_LENGTH)

#endif

#ifndef OPENSSL_NO_MDC2

/* MDC-2 (2 5 8 3 101) */

static const unsigned char digestinfo_mdc2_der[] = {

    ASN1_SEQUENCE, 0x0c + MDC2_DIGEST_LENGTH,

    ASN1_SEQUENCE, 0x08,

    ASN1_OID, 0x04, 2 * 40 + 5, 8, 3, 101,

    ASN1_NULL, 0x00,

    ASN1_OCTET_STRING, MDC2_DIGEST_LENGTH

};

#endif

#ifndef OPENSSL_NO_RMD160

/* RIPEMD160 (1 3 36 3 2 1) */

static const unsigned char digestinfo_ripemd160_der[] = {

    ASN1_SEQUENCE, 0x0d + RIPEMD160_DIGEST_LENGTH,

    ASN1_SEQUENCE, 0x09,

    ASN1_OID, 0x05, 1 * 40 + 3, 36, 3, 2, 1,

    ASN1_NULL, 0x00,

    ASN1_OCTET_STRING, RIPEMD160_DIGEST_LENGTH

};

#endif

#endif /* FIPS_MODULE */

/* SHA-1 (1 3 14 3 2 26) */

static const unsigned char digestinfo_sha1_der[] = {

    ASN1_SEQUENCE, 0x0d + SHA_DIGEST_LENGTH,

    ASN1_SEQUENCE, 0x09,

    ASN1_OID, 0x05, 1 * 40 + 3, 14, 3, 2, 26,

    ASN1_NULL, 0x00,

    ASN1_OCTET_STRING, SHA_DIGEST_LENGTH

};

ENCODE_DIGESTINFO_SHA(sha256, 0x01, SHA256_DIGEST_LENGTH)

ENCODE_DIGESTINFO_SHA(sha384, 0x02, SHA384_DIGEST_LENGTH)

ENCODE_DIGESTINFO_SHA(sha512, 0x03, SHA512_DIGEST_LENGTH)

ENCODE_DIGESTINFO_SHA(sha224, 0x04, SHA224_DIGEST_LENGTH)

ENCODE_DIGESTINFO_SHA(sha512_224, 0x05, SHA224_DIGEST_LENGTH)

ENCODE_DIGESTINFO_SHA(sha512_256, 0x06, SHA256_DIGEST_LENGTH)

ENCODE_DIGESTINFO_SHA(sha3_224, 0x07, SHA224_DIGEST_LENGTH)

ENCODE_DIGESTINFO_SHA(sha3_256, 0x08, SHA256_DIGEST_LENGTH)

ENCODE_DIGESTINFO_SHA(sha3_384, 0x09, SHA384_DIGEST_LENGTH)

ENCODE_DIGESTINFO_SHA(sha3_512, 0x0a, SHA512_DIGEST_LENGTH)

#define MD_CASE(name)                           \

    case NID_##name:                            \

        *len = sizeof(digestinfo_##name##_der); \

        return digestinfo_##name##_der;

const unsigned char *ossl_rsa_digestinfo_encoding(int md_nid, size_t *len)

{

    switch (md_nid) {

#ifndef FIPS_MODULE

#ifndef OPENSSL_NO_MDC2

        MD_CASE(mdc2)

#endif

#ifndef OPENSSL_NO_MD2

        MD_CASE(md2)

#endif

#ifndef OPENSSL_NO_MD4

        MD_CASE(md4)

#endif

#ifndef OPENSSL_NO_MD5

        MD_CASE(md5)

#endif

#ifndef OPENSSL_NO_RMD160

        MD_CASE(ripemd160)

#endif

#endif /* FIPS_MODULE */

        MD_CASE(sha1)

        MD_CASE(sha224)

        MD_CASE(sha256)

        MD_CASE(sha384)

        MD_CASE(sha512)

        MD_CASE(sha512_224)

        MD_CASE(sha512_256)

        MD_CASE(sha3_224)

        MD_CASE(sha3_256)

        MD_CASE(sha3_384)

        MD_CASE(sha3_512)

    default:

        return NULL;

    }

}

#define MD_NID_CASE(name, sz) \

    case NID_##name:          \

        return sz;

static int digest_sz_from_nid(int nid)

{

    switch (nid) {

#ifndef FIPS_MODULE

#ifndef OPENSSL_NO_MDC2

        MD_NID_CASE(mdc2, MDC2_DIGEST_LENGTH)

#endif

#ifndef OPENSSL_NO_MD2

        MD_NID_CASE(md2, MD2_DIGEST_LENGTH)

#endif

#ifndef OPENSSL_NO_MD4

        MD_NID_CASE(md4, MD4_DIGEST_LENGTH)

#endif

#ifndef OPENSSL_NO_MD5

        MD_NID_CASE(md5, MD5_DIGEST_LENGTH)

#endif

#ifndef OPENSSL_NO_RMD160

        MD_NID_CASE(ripemd160, RIPEMD160_DIGEST_LENGTH)

#endif

#endif /* FIPS_MODULE */

        MD_NID_CASE(sha1, SHA_DIGEST_LENGTH)

        MD_NID_CASE(sha224, SHA224_DIGEST_LENGTH)

        MD_NID_CASE(sha256, SHA256_DIGEST_LENGTH)

        MD_NID_CASE(sha384, SHA384_DIGEST_LENGTH)

        MD_NID_CASE(sha512, SHA512_DIGEST_LENGTH)

        MD_NID_CASE(sha512_224, SHA224_DIGEST_LENGTH)

        MD_NID_CASE(sha512_256, SHA256_DIGEST_LENGTH)

        MD_NID_CASE(sha3_224, SHA224_DIGEST_LENGTH)

        MD_NID_CASE(sha3_256, SHA256_DIGEST_LENGTH)

        MD_NID_CASE(sha3_384, SHA384_DIGEST_LENGTH)

        MD_NID_CASE(sha3_512, SHA512_DIGEST_LENGTH)

    default:

        return 0;

    }

}

/* Size of an SSL signature: MD5+SHA1 */

#define SSL_SIG_LENGTH 36

/*

 * Encodes a DigestInfo prefix of hash |type| and digest |m|, as

 * described in EMSA-PKCS1-v1_5-ENCODE, RFC 3447 section 9.2 step 2. This

 * encodes the DigestInfo (T and tLen) but does not add the padding.

 *

 * On success, it returns one and sets |*out| to a newly allocated buffer

 * containing the result and |*out_len| to its length. The caller must free

 * |*out| with OPENSSL_free(). Otherwise, it returns zero.

 */

static int encode_pkcs1(unsigned char **out, size_t *out_len, int type,

    const unsigned char *m, size_t m_len)

{

    size_t di_prefix_len, dig_info_len;

    const unsigned char *di_prefix;

    unsigned char *dig_info;

    if (type == NID_undef) {

        ERR_raise(ERR_LIB_RSA, RSA_R_UNKNOWN_ALGORITHM_TYPE);

        return 0;

    }

    di_prefix = ossl_rsa_digestinfo_encoding(type, &di_prefix_len);

    if (di_prefix == NULL) {

        ERR_raise(ERR_LIB_RSA,

            RSA_R_THE_ASN1_OBJECT_IDENTIFIER_IS_NOT_KNOWN_FOR_THIS_MD);

        return 0;

    }

    dig_info_len = di_prefix_len + m_len;

    dig_info = OPENSSL_malloc(dig_info_len);

    if (dig_info == NULL)

        return 0;

    memcpy(dig_info, di_prefix, di_prefix_len);

    memcpy(dig_info + di_prefix_len, m, m_len);

    *out = dig_info;

    *out_len = dig_info_len;

    return 1;

}

int RSA_sign(int type, const unsigned char *m, unsigned int m_len,

    unsigned char *sigret, unsigned int *siglen, RSA *rsa)

{

    int encrypt_len, ret = 0;

    size_t encoded_len = 0;

    unsigned char *tmps = NULL;

    const unsigned char *encoded = NULL;

#ifndef FIPS_MODULE

    if (rsa->meth->rsa_sign != NULL)

        return rsa->meth->rsa_sign(type, m, m_len, sigret, siglen, rsa) > 0;

#endif /* FIPS_MODULE */

    /* Compute the encoded digest. */

    if (type == NID_md5_sha1) {

        /*

         * NID_md5_sha1 corresponds to the MD5/SHA1 combination in TLS 1.1 and

         * earlier. It has no DigestInfo wrapper but otherwise is

         * RSASSA-PKCS1-v1_5.

         */

        if (m_len != SSL_SIG_LENGTH) {

            ERR_raise(ERR_LIB_RSA, RSA_R_INVALID_MESSAGE_LENGTH);

            return 0;

        }

        encoded_len = SSL_SIG_LENGTH;

        encoded = m;

    } else {

        if (!encode_pkcs1(&tmps, &encoded_len, type, m, m_len))

            goto err;

        encoded = tmps;

    }

    if (encoded_len + RSA_PKCS1_PADDING_SIZE > (size_t)RSA_size(rsa)) {

        ERR_raise(ERR_LIB_RSA, RSA_R_DIGEST_TOO_BIG_FOR_RSA_KEY);

        goto err;

    }

    encrypt_len = RSA_private_encrypt((int)encoded_len, encoded, sigret, rsa,

        RSA_PKCS1_PADDING);

    if (encrypt_len <= 0)

        goto err;

    *siglen = encrypt_len;

    ret = 1;

err:

    OPENSSL_clear_free(tmps, encoded_len);

    return ret;

}

/*

 * Verify an RSA signature in |sigbuf| using |rsa|.

 * |type| is the NID of the digest algorithm to use.

 * If |rm| is NULL, it verifies the signature for digest |m|, otherwise

 * it recovers the digest from the signature, writing the digest to |rm| and

 * the length to |*prm_len|.

 *

 * It returns one on successful verification or zero otherwise.

 */

int ossl_rsa_verify(int type, const unsigned char *m, unsigned int m_len,

    unsigned char *rm, size_t *prm_len,

    const unsigned char *sigbuf, size_t siglen, RSA *rsa)

{

    int len, ret = 0;

    size_t decrypt_len, encoded_len = 0;

    unsigned char *decrypt_buf = NULL, *encoded = NULL;

    if (siglen != (size_t)RSA_size(rsa)) {

        ERR_raise(ERR_LIB_RSA, RSA_R_WRONG_SIGNATURE_LENGTH);

        return 0;

    }

    /* Recover the encoded digest. */

    decrypt_buf = OPENSSL_malloc(siglen);

    if (decrypt_buf == NULL)

        goto err;

    len = RSA_public_decrypt((int)siglen, sigbuf, decrypt_buf, rsa,

        RSA_PKCS1_PADDING);

    if (len <= 0)

        goto err;

    decrypt_len = len;

#ifndef FIPS_MODULE

    if (type == NID_md5_sha1) {

        /*

         * NID_md5_sha1 corresponds to the MD5/SHA1 combination in TLS 1.1 and

         * earlier. It has no DigestInfo wrapper but otherwise is

         * RSASSA-PKCS1-v1_5.

         */

        if (decrypt_len != SSL_SIG_LENGTH) {

            ERR_raise(ERR_LIB_RSA, RSA_R_BAD_SIGNATURE);

            goto err;

        }

        if (rm != NULL) {

            memcpy(rm, decrypt_buf, SSL_SIG_LENGTH);

            *prm_len = SSL_SIG_LENGTH;

        } else {

            if (m_len != SSL_SIG_LENGTH) {

                ERR_raise(ERR_LIB_RSA, RSA_R_INVALID_MESSAGE_LENGTH);

                goto err;

            }

            if (memcmp(decrypt_buf, m, SSL_SIG_LENGTH) != 0) {

                ERR_raise(ERR_LIB_RSA, RSA_R_BAD_SIGNATURE);

                goto err;

            }

        }

    } else if (type == NID_mdc2 && decrypt_len == 2 + 16

        && decrypt_buf[0] == 0x04 && decrypt_buf[1] == 0x10) {

        /*

         * Oddball MDC2 case: signature can be OCTET STRING. check for correct

         * tag and length octets.

         */

        if (rm != NULL) {

            memcpy(rm, decrypt_buf + 2, 16);

            *prm_len = 16;

        } else {

            if (m_len != 16) {

                ERR_raise(ERR_LIB_RSA, RSA_R_INVALID_MESSAGE_LENGTH);

                goto err;

            }

            if (memcmp(m, decrypt_buf + 2, 16) != 0) {

                ERR_raise(ERR_LIB_RSA, RSA_R_BAD_SIGNATURE);

                goto err;

            }

        }

    } else

#endif /* FIPS_MODULE */

    {

        /*

         * If recovering the digest, extract a digest-sized output from the end

         * of |decrypt_buf| for |encode_pkcs1|, then compare the decryption

         * output as in a standard verification.

         */

        if (rm != NULL) {

            len = digest_sz_from_nid(type);

            if (len <= 0)

                goto err;

            m_len = (unsigned int)len;

            if (m_len > decrypt_len) {

                ERR_raise(ERR_LIB_RSA, RSA_R_INVALID_DIGEST_LENGTH);

                goto err;

            }

            m = decrypt_buf + decrypt_len - m_len;

        }

        /* Construct the encoded digest and ensure it matches. */

        if (!encode_pkcs1(&encoded, &encoded_len, type, m, m_len))

            goto err;

        if (encoded_len != decrypt_len

            || memcmp(encoded, decrypt_buf, encoded_len) != 0) {

            ERR_raise(ERR_LIB_RSA, RSA_R_BAD_SIGNATURE);

            goto err;

        }

        /* Output the recovered digest. */

        if (rm != NULL) {

            memcpy(rm, m, m_len);

            *prm_len = m_len;

        }

    }

    ret = 1;

err:

    OPENSSL_clear_free(encoded, encoded_len);

    OPENSSL_clear_free(decrypt_buf, siglen);

    return ret;

}

int RSA_verify(int type, const unsigned char *m, unsigned int m_len,

    const unsigned char *sigbuf, unsigned int siglen, RSA *rsa)

{

    if (rsa->meth->rsa_verify != NULL)

        return rsa->meth->rsa_verify(type, m, m_len, sigbuf, siglen, rsa);

    return ossl_rsa_verify(type, m, m_len, NULL, NULL, sigbuf, siglen, rsa);

}