diff options
Diffstat (limited to 'bdb/dump_rsa.c')
| -rw-r--r-- | bdb/dump_rsa.c | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/bdb/dump_rsa.c b/bdb/dump_rsa.c new file mode 100644 index 00000000..c40f803a --- /dev/null +++ b/bdb/dump_rsa.c @@ -0,0 +1,200 @@ +/* Copyright (c) 2010 The Chromium OS Authors. All rights reserved. + * Use of this source code is governed by a BSD-style license that can be + * found in the LICENSE file. + */ + +/* + * C port of DumpPublicKey.java from the Android Open source project with + * support for additional RSA key sizes. (platform/system/core,git/libmincrypt + * /tools/DumpPublicKey.java). Uses the OpenSSL X509 and BIGNUM library. + */ + +#include <openssl/pem.h> + +#include <stdint.h> +#include <string.h> +#include <unistd.h> + +/* + * Command line tool to extract RSA public keys from X.509 certificates and + * output a pre-processed version of keys for use by RSA verification routines. + */ + +int check(RSA *key) +{ + int public_exponent = BN_get_word(key->e); + int modulus = BN_num_bits(key->n); + + if (public_exponent != 65537 && public_exponent != 3) { + fprintf(stderr, "WARNING: Non-standard public exponent %d.\n", + public_exponent); + } + + if (modulus != 1024 && modulus != 2048 && modulus != 3072 && + modulus != 4096 && modulus != 8192) { + fprintf(stderr, "WARNING: Non-standard modulus length = %d.\n", + modulus); + } + return 1; +} + +/** + * Pre-processes and outputs RSA public key to standard output. + */ +void output(RSA *key) +{ + BIGNUM *N; + BIGNUM *Big1 = NULL, *Big2 = NULL, *Big32 = NULL, *BigMinus1 = NULL; + BIGNUM *B = NULL; + BIGNUM *N0inv= NULL, *R = NULL, *RR = NULL, *RRTemp = NULL; + BIGNUM *NnumBits = NULL; + BIGNUM *n = NULL, *rr = NULL; + BN_CTX *bn_ctx = BN_CTX_new(); + uint32_t n0invout; + int nwords, i; + + N = key->n; + /* Output size of RSA key in 32-bit words */ + nwords = BN_num_bits(N) / 32; + if (-1 == write(1, &nwords, sizeof(nwords))) + goto failure; + + /* Initialize BIGNUMs */ + Big1 = BN_new(); + Big2 = BN_new(); + Big32 = BN_new(); + BigMinus1 = BN_new(); + N0inv= BN_new(); + R = BN_new(); + RR = BN_new(); + RRTemp = BN_new(); + NnumBits = BN_new(); + n = BN_new(); + rr = BN_new(); + + BN_set_word(Big1, 1L); + BN_set_word(Big2, 2L); + BN_set_word(Big32, 32L); + BN_sub(BigMinus1, Big1, Big2); + + B = BN_new(); + BN_exp(B, Big2, Big32, bn_ctx); /* B = 2^32 */ + + /* Calculate and output N0inv = -1 / N[0] mod 2^32 */ + BN_mod_inverse(N0inv, N, B, bn_ctx); + BN_sub(N0inv, B, N0inv); + n0invout = BN_get_word(N0inv); + if (-1 == write(1, &n0invout, sizeof(n0invout))) + goto failure; + + /* Calculate R = 2^(# of key bits) */ + BN_set_word(NnumBits, BN_num_bits(N)); + BN_exp(R, Big2, NnumBits, bn_ctx); + + /* Calculate RR = R^2 mod N */ + BN_copy(RR, R); + BN_mul(RRTemp, RR, R, bn_ctx); + BN_mod(RR, RRTemp, N, bn_ctx); + + /* Write out modulus as little endian array of integers. */ + for (i = 0; i < nwords; ++i) { + uint32_t nout; + + BN_mod(n, N, B, bn_ctx); /* n = N mod B */ + nout = BN_get_word(n); + if (-1 == write(1, &nout, sizeof(nout))) + goto failure; + + BN_rshift(N, N, 32); /* N = N/B */ + } + + /* Write R^2 as little endian array of integers. */ + for (i = 0; i < nwords; ++i) { + uint32_t rrout; + + BN_mod(rr, RR, B, bn_ctx); /* rr = RR mod B */ + rrout = BN_get_word(rr); + if (-1 == write(1, &rrout, sizeof(rrout))) + goto failure; + + BN_rshift(RR, RR, 32); /* RR = RR/B */ + } + + failure: + /* Free BIGNUMs. */ + BN_free(Big1); + BN_free(Big2); + BN_free(Big32); + BN_free(BigMinus1); + BN_free(N0inv); + BN_free(R); + BN_free(RRTemp); + BN_free(NnumBits); + BN_free(n); + BN_free(rr); + +} + +int main(int argc, char* argv[]) { + int cert_mode = 0; + FILE* fp; + X509* cert = NULL; + RSA* pubkey = NULL; + EVP_PKEY* key; + char *progname; + + if (argc != 3 || + (strcmp(argv[1], "-cert") && strcmp(argv[1], "-pub"))) { + progname = strrchr(argv[0], '/'); + if (progname) + progname++; + else + progname = argv[0]; + fprintf(stderr, "Usage: %s <-cert | -pub> <file>\n", progname); + return -1; + } + + if (!strcmp(argv[1], "-cert")) + cert_mode = 1; + + fp = fopen(argv[2], "r"); + + if (!fp) { + fprintf(stderr, "Couldn't open file %s!\n", argv[2]); + return -1; + } + + if (cert_mode) { + /* Read the certificate */ + if (!PEM_read_X509(fp, &cert, NULL, NULL)) { + fprintf(stderr, "Couldn't read certificate.\n"); + goto fail; + } + + /* Get the public key from the certificate. */ + key = X509_get_pubkey(cert); + + /* Convert to a RSA_style key. */ + if (!(pubkey = EVP_PKEY_get1_RSA(key))) { + fprintf(stderr, "Couldn't convert to RSA style key.\n"); + goto fail; + } + } else { + /* Read the pubkey in .PEM format. */ + if (!(pubkey = PEM_read_RSA_PUBKEY(fp, NULL, NULL, NULL))) { + fprintf(stderr, "Couldn't read public key file.\n"); + goto fail; + } + } + + if (check(pubkey)) { + output(pubkey); + } + + fail: + X509_free(cert); + RSA_free(pubkey); + fclose(fp); + + return 0; +} |