Original axtls RSA code

src/crypto/axtls/rsa.c

@@ -0,0 +1,331 @@
+/*
+ *  Copyright(C) 2006 Cameron Rich
+ *
+ *  This library is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU Lesser General Public License as published by
+ *  the Free Software Foundation; either version 2.1 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public License
+ *  along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+/**
+ * Implements the RSA public encryption algorithm. Uses the bigint library to
+ * perform its calculations.
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <time.h>
+#include <stdlib.h>
+#include "crypto.h"
+
+#ifdef CONFIG_BIGINT_CRT
+static bigint *bi_crt(RSA_CTX *rsa, bigint *bi);
+#endif
+
+void RSA_priv_key_new(RSA_CTX **ctx, 
+        const uint8_t *modulus, int mod_len,
+        const uint8_t *pub_exp, int pub_len,
+        const uint8_t *priv_exp, int priv_len
+#if CONFIG_BIGINT_CRT
+      , const uint8_t *p, int p_len,
+        const uint8_t *q, int q_len,
+        const uint8_t *dP, int dP_len,
+        const uint8_t *dQ, int dQ_len,
+        const uint8_t *qInv, int qInv_len
+#endif
+    )
+{
+    RSA_CTX *rsa_ctx;
+    BI_CTX *bi_ctx;
+    RSA_pub_key_new(ctx, modulus, mod_len, pub_exp, pub_len);
+    rsa_ctx = *ctx;
+    bi_ctx = rsa_ctx->bi_ctx;
+    rsa_ctx->d = bi_import(bi_ctx, priv_exp, priv_len);
+    bi_permanent(rsa_ctx->d);
+
+#ifdef CONFIG_BIGINT_CRT
+    rsa_ctx->p = bi_import(bi_ctx, p, p_len);
+    rsa_ctx->q = bi_import(bi_ctx, q, q_len);
+    rsa_ctx->dP = bi_import(bi_ctx, dP, dP_len);
+    rsa_ctx->dQ = bi_import(bi_ctx, dQ, dQ_len);
+    rsa_ctx->qInv = bi_import(bi_ctx, qInv, qInv_len);
+    bi_permanent(rsa_ctx->dP);
+    bi_permanent(rsa_ctx->dQ);
+    bi_permanent(rsa_ctx->qInv);
+    bi_set_mod(bi_ctx, rsa_ctx->p, BIGINT_P_OFFSET);
+    bi_set_mod(bi_ctx, rsa_ctx->q, BIGINT_Q_OFFSET);
+#endif
+}
+
+void RSA_pub_key_new(RSA_CTX **ctx, 
+        const uint8_t *modulus, int mod_len,
+        const uint8_t *pub_exp, int pub_len)
+{
+    RSA_CTX *rsa_ctx;
+    BI_CTX *bi_ctx = bi_initialize();
+    *ctx = (RSA_CTX *)calloc(1, sizeof(RSA_CTX));   /* reset to all 0 */
+    rsa_ctx = *ctx;
+    rsa_ctx->bi_ctx = bi_ctx;
+    rsa_ctx->num_octets = (mod_len & 0xFFF0);
+    rsa_ctx->m = bi_import(bi_ctx, modulus, mod_len);
+    bi_set_mod(bi_ctx, rsa_ctx->m, BIGINT_M_OFFSET);
+    rsa_ctx->e = bi_import(bi_ctx, pub_exp, pub_len);
+    bi_permanent(rsa_ctx->e);
+}
+
+/**
+ * Free up any RSA context resources.
+ */
+void RSA_free(RSA_CTX *rsa_ctx)
+{
+    BI_CTX *bi_ctx;
+    if (rsa_ctx == NULL)                /* deal with ptrs that are null */
+        return;
+
+    bi_ctx = rsa_ctx->bi_ctx;
+
+    bi_depermanent(rsa_ctx->e);
+    bi_free(bi_ctx, rsa_ctx->e);
+    bi_free_mod(rsa_ctx->bi_ctx, BIGINT_M_OFFSET);
+
+    if (rsa_ctx->d)
+    {
+        bi_depermanent(rsa_ctx->d);
+        bi_free(bi_ctx, rsa_ctx->d);
+#ifdef CONFIG_BIGINT_CRT
+        bi_depermanent(rsa_ctx->dP);
+        bi_depermanent(rsa_ctx->dQ);
+        bi_depermanent(rsa_ctx->qInv);
+        bi_free(bi_ctx, rsa_ctx->dP);
+        bi_free(bi_ctx, rsa_ctx->dQ);
+        bi_free(bi_ctx, rsa_ctx->qInv);
+        bi_free_mod(rsa_ctx->bi_ctx, BIGINT_P_OFFSET);
+        bi_free_mod(rsa_ctx->bi_ctx, BIGINT_Q_OFFSET);
+#endif
+    }
+
+    bi_terminate(bi_ctx);
+    free(rsa_ctx);
+}
+
+/**
+ * @brief Use PKCS1.5 for decryption/verification.
+ * @param ctx [in] The context
+ * @param in_data [in] The data to encrypt (must be < modulus size-11)
+ * @param out_data [out] The encrypted data.
+ * @param is_decryption [in] Decryption or verify operation.
+ * @return  The number of bytes that were originally encrypted. -1 on error.
+ * @see http://www.rsasecurity.com/rsalabs/node.asp?id=2125
+ */
+int RSA_decrypt(RSA_CTX *ctx, const uint8_t *in_data, uint8_t *out_data,
+        int is_decryption)
+{
+    int byte_size = ctx->num_octets;
+    uint8_t *block;
+    int i, size;
+    bigint *decrypted_bi, *dat_bi;
+
+    memset(out_data, 0, byte_size); /* initialise */
+
+    /* decrypt */
+    dat_bi = bi_import(ctx->bi_ctx, in_data, byte_size);
+#ifdef CONFIG_SSL_CERT_VERIFICATION
+    decrypted_bi = is_decryption ?  /* decrypt or verify? */
+            RSA_private(ctx, dat_bi) : RSA_public(ctx, dat_bi);
+#else   /* always a decryption */
+    decrypted_bi = RSA_private(ctx, dat_bi);
+#endif
+
+    /* convert to a normal block */
+    block = (uint8_t *)malloc(byte_size);
+    bi_export(ctx->bi_ctx, decrypted_bi, block, byte_size);
+
+    i = 10; /* start at the first possible non-padded byte */
+
+#ifdef CONFIG_SSL_CERT_VERIFICATION
+    if (is_decryption == 0) /* PKCS1.5 signing pads with "0xff"s */
+    {
+        while (block[i++] == 0xff && i < byte_size);
+        if (block[i-2] != 0xff)
+        {
+            i = byte_size;     /*ensure size is 0 */   
+        }
+    }
+    else                    /* PKCS1.5 encryption padding is random */
+#endif
+    {
+        while (block[i++] && i < byte_size);
+    }
+    size = byte_size - i;
+
+    /* get only the bit we want */
+    if (size > 0)
+    {
+        memcpy(out_data, &block[i], size);
+    }
+    
+    free(block);
+    return size ? size : -1;
+}
+
+/**
+ * Performs m = c^d mod n
+ */
+bigint *RSA_private(RSA_CTX *c, bigint *bi_msg)
+{
+#ifdef CONFIG_BIGINT_CRT
+    return bi_crt(c, bi_msg);
+#else
+    BI_CTX *ctx = c->bi_ctx;
+    ctx->mod_offset = BIGINT_M_OFFSET;
+    return bi_mod_power(ctx, bi_msg, c->d);
+#endif
+}
+
+#ifdef CONFIG_BIGINT_CRT
+/**
+ * Use the Chinese Remainder Theorem to quickly perform RSA decrypts.
+ * This should really be in bigint.c (and was at one stage), but needs 
+ * access to the RSA_CTX context...
+ */
+static bigint *bi_crt(RSA_CTX *rsa, bigint *bi)
+{
+    BI_CTX *ctx = rsa->bi_ctx;
+    bigint *m1, *m2, *h;
+
+    /* Montgomery has a condition the 0 < x, y < m and these products violate
+     * that condition. So disable Montgomery when using CRT */
+#if defined(CONFIG_BIGINT_MONTGOMERY)
+    ctx->use_classical = 1;
+#endif
+    ctx->mod_offset = BIGINT_P_OFFSET;
+    m1 = bi_mod_power(ctx, bi_copy(bi), rsa->dP);
+
+    ctx->mod_offset = BIGINT_Q_OFFSET;
+    m2 = bi_mod_power(ctx, bi, rsa->dQ);
+
+    h = bi_subtract(ctx, bi_add(ctx, m1, rsa->p), bi_copy(m2), NULL);
+    h = bi_multiply(ctx, h, rsa->qInv);
+    ctx->mod_offset = BIGINT_P_OFFSET;
+    h = bi_residue(ctx, h);
+#if defined(CONFIG_BIGINT_MONTGOMERY)
+    ctx->use_classical = 0;         /* reset for any further operation */
+#endif
+    return bi_add(ctx, m2, bi_multiply(ctx, rsa->q, h));
+}
+#endif
+
+#ifdef CONFIG_SSL_FULL_MODE
+/**
+ * Used for diagnostics.
+ */
+void RSA_print(const RSA_CTX *rsa_ctx) 
+{
+    if (rsa_ctx == NULL)
+        return;
+
+    printf("-----------------   RSA DEBUG   ----------------\n");
+    printf("Size:\t%d\n", rsa_ctx->num_octets);
+    bi_print("Modulus", rsa_ctx->m);
+    bi_print("Public Key", rsa_ctx->e);
+    bi_print("Private Key", rsa_ctx->d);
+}
+#endif
+
+#ifdef CONFIG_SSL_CERT_VERIFICATION
+/**
+ * Performs c = m^e mod n
+ */
+bigint *RSA_public(RSA_CTX *c, bigint *bi_msg)
+{
+    c->bi_ctx->mod_offset = BIGINT_M_OFFSET;
+    return bi_mod_power(c->bi_ctx, bi_msg, c->e);
+}
+
+/**
+ * Use PKCS1.5 for encryption/signing.
+ * see http://www.rsasecurity.com/rsalabs/node.asp?id=2125
+ */
+int RSA_encrypt(RSA_CTX *ctx, const uint8_t *in_data, uint16_t in_len, 
+        uint8_t *out_data, int is_signing)
+{
+    int byte_size = ctx->num_octets;
+    int num_pads_needed = byte_size-in_len-3;
+    bigint *dat_bi, *encrypt_bi;
+
+    /* note: in_len+11 must be > byte_size */
+    out_data[0] = 0;     /* ensure encryption block is < modulus */
+
+    if (is_signing)
+    {
+        out_data[1] = 1;        /* PKCS1.5 signing pads with "0xff"'s */
+        memset(&out_data[2], 0xff, num_pads_needed);
+    }
+    else /* randomize the encryption padding with non-zero bytes */   
+    {
+        out_data[1] = 2;
+        get_random_NZ(num_pads_needed, &out_data[2]);
+    }
+
+    out_data[2+num_pads_needed] = 0;
+    memcpy(&out_data[3+num_pads_needed], in_data, in_len);
+
+    /* now encrypt it */
+    dat_bi = bi_import(ctx->bi_ctx, out_data, byte_size);
+    encrypt_bi = is_signing ? RSA_private(ctx, dat_bi) : 
+        RSA_public(ctx, dat_bi);
+    bi_export(ctx->bi_ctx, encrypt_bi, out_data, byte_size);
+    return byte_size;
+}
+
+/**
+ * Take a signature and decrypt it.
+ */
+bigint *RSA_sign_verify(BI_CTX *ctx, const uint8_t *sig, int sig_len,
+        bigint *modulus, bigint *pub_exp)
+{
+    uint8_t *block = (uint8_t *)malloc(sig_len);
+    int i, size;
+    bigint *decrypted_bi, *dat_bi;
+    bigint *bir = NULL;
+
+    /* decrypt */
+    dat_bi = bi_import(ctx, sig, sig_len);
+    ctx->mod_offset = BIGINT_M_OFFSET;
+
+    /* convert to a normal block */
+    decrypted_bi = bi_mod_power2(ctx, dat_bi, modulus, pub_exp);
+
+    bi_export(ctx, decrypted_bi, block, sig_len);
+    ctx->mod_offset = BIGINT_M_OFFSET;
+
+    i = 10; /* start at the first possible non-padded byte */
+    while (block[i++] && i < sig_len);
+    size = sig_len - i;
+
+    /* get only the bit we want */
+    if (size > 0)
+    {
+        int len;
+        const uint8_t *sig_ptr = x509_get_signature(&block[i], &len);
+
+        if (sig_ptr)
+        {
+            bir = bi_import(ctx, sig_ptr, len);
+        }
+    }
+
+    free(block);
+    return bir;
+}
+
+#endif  /* CONFIG_SSL_CERT_VERIFICATION */