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| 1 /* crypto/aes/aes_ctr.c -*- mode:C; c-file-style: "eay" -*- */ | 1 /* crypto/aes/aes_ctr.c -*- mode:C; c-file-style: "eay" -*- */ |
| 2 /* ==================================================================== | 2 /* ==================================================================== |
| 3 * Copyright (c) 1998-2002 The OpenSSL Project. All rights reserved. | 3 * Copyright (c) 1998-2002 The OpenSSL Project. All rights reserved. |
| 4 * | 4 * |
| 5 * Redistribution and use in source and binary forms, with or without | 5 * Redistribution and use in source and binary forms, with or without |
| 6 * modification, are permitted provided that the following conditions | 6 * modification, are permitted provided that the following conditions |
| 7 * are met: | 7 * are met: |
| 8 * | 8 * |
| 9 * 1. Redistributions of source code must retain the above copyright | 9 * 1. Redistributions of source code must retain the above copyright |
| 10 * notice, this list of conditions and the following disclaimer. | 10 * notice, this list of conditions and the following disclaimer. |
| (...skipping 31 matching lines...) Expand 10 before | Expand all | Expand 10 after Loading... |
| 42 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; | 42 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| 43 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | 43 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 44 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, | 44 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
| 45 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | 45 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 46 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED | 46 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED |
| 47 * OF THE POSSIBILITY OF SUCH DAMAGE. | 47 * OF THE POSSIBILITY OF SUCH DAMAGE. |
| 48 * ==================================================================== | 48 * ==================================================================== |
| 49 * | 49 * |
| 50 */ | 50 */ |
| 51 | 51 |
| 52 #ifndef AES_DEBUG | 52 #include <openssl/aes.h> |
| 53 # ifndef NDEBUG | 53 #include <openssl/modes.h> |
| 54 # define NDEBUG | |
| 55 # endif | |
| 56 #endif | |
| 57 #include <assert.h> | |
| 58 | 54 |
| 59 #include <openssl/aes.h> | 55 void AES_ctr128_encrypt(const unsigned char *in, unsigned char *out, |
| 60 #include "aes_locl.h" | 56 » » » size_t length, const AES_KEY *key, |
| 61 | 57 » » » unsigned char ivec[AES_BLOCK_SIZE], |
| 62 /* NOTE: the IV/counter CTR mode is big-endian. The rest of the AES code | 58 » » » unsigned char ecount_buf[AES_BLOCK_SIZE], |
| 63 * is endian-neutral. */ | 59 » » » unsigned int *num) { |
| 64 | 60 » CRYPTO_ctr128_encrypt(in,out,length,key,ivec,ecount_buf,num,(block128_f)
AES_encrypt); |
| 65 /* increment counter (128-bit int) by 1 */ | |
| 66 static void AES_ctr128_inc(unsigned char *counter) { | |
| 67 » unsigned long c; | |
| 68 | |
| 69 » /* Grab bottom dword of counter and increment */ | |
| 70 » c = GETU32(counter + 12); | |
| 71 » c++;» c &= 0xFFFFFFFF; | |
| 72 » PUTU32(counter + 12, c); | |
| 73 | |
| 74 » /* if no overflow, we're done */ | |
| 75 » if (c) | |
| 76 » » return; | |
| 77 | |
| 78 » /* Grab 1st dword of counter and increment */ | |
| 79 » c = GETU32(counter + 8); | |
| 80 » c++;» c &= 0xFFFFFFFF; | |
| 81 » PUTU32(counter + 8, c); | |
| 82 | |
| 83 » /* if no overflow, we're done */ | |
| 84 » if (c) | |
| 85 » » return; | |
| 86 | |
| 87 » /* Grab 2nd dword of counter and increment */ | |
| 88 » c = GETU32(counter + 4); | |
| 89 » c++;» c &= 0xFFFFFFFF; | |
| 90 » PUTU32(counter + 4, c); | |
| 91 | |
| 92 » /* if no overflow, we're done */ | |
| 93 » if (c) | |
| 94 » » return; | |
| 95 | |
| 96 » /* Grab top dword of counter and increment */ | |
| 97 » c = GETU32(counter + 0); | |
| 98 » c++;» c &= 0xFFFFFFFF; | |
| 99 » PUTU32(counter + 0, c); | |
| 100 } | 61 } |
| 101 | |
| 102 /* The input encrypted as though 128bit counter mode is being | |
| 103 * used. The extra state information to record how much of the | |
| 104 * 128bit block we have used is contained in *num, and the | |
| 105 * encrypted counter is kept in ecount_buf. Both *num and | |
| 106 * ecount_buf must be initialised with zeros before the first | |
| 107 * call to AES_ctr128_encrypt(). | |
| 108 * | |
| 109 * This algorithm assumes that the counter is in the x lower bits | |
| 110 * of the IV (ivec), and that the application has full control over | |
| 111 * overflow and the rest of the IV. This implementation takes NO | |
| 112 * responsability for checking that the counter doesn't overflow | |
| 113 * into the rest of the IV when incremented. | |
| 114 */ | |
| 115 void AES_ctr128_encrypt(const unsigned char *in, unsigned char *out, | |
| 116 const unsigned long length, const AES_KEY *key, | |
| 117 unsigned char ivec[AES_BLOCK_SIZE], | |
| 118 unsigned char ecount_buf[AES_BLOCK_SIZE], | |
| 119 unsigned int *num) { | |
| 120 | |
| 121 unsigned int n; | |
| 122 unsigned long l=length; | |
| 123 | |
| 124 assert(in && out && key && counter && num); | |
| 125 assert(*num < AES_BLOCK_SIZE); | |
| 126 | |
| 127 n = *num; | |
| 128 | |
| 129 while (l--) { | |
| 130 if (n == 0) { | |
| 131 AES_encrypt(ivec, ecount_buf, key); | |
| 132 AES_ctr128_inc(ivec); | |
| 133 } | |
| 134 *(out++) = *(in++) ^ ecount_buf[n]; | |
| 135 n = (n+1) % AES_BLOCK_SIZE; | |
| 136 } | |
| 137 | |
| 138 *num=n; | |
| 139 } | |
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