From 5b50281100f3b6ac227de40caf906302c1c909ec Mon Sep 17 00:00:00 2001 From: Christopher Wellons Date: Fri, 3 Mar 2017 11:22:36 -0500 Subject: [PATCH] Add authentication checksum. --- Makefile | 3 +- enchive.c | 58 +++++++++++++++++++- machine.h | 1 + sha256.c | 158 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ sha256.h | 33 ++++++++++++ 5 files changed, 250 insertions(+), 3 deletions(-) create mode 100644 sha256.c create mode 100644 sha256.h diff --git a/Makefile b/Makefile index 7724b20..ee6ba77 100644 --- a/Makefile +++ b/Makefile @@ -3,13 +3,14 @@ CC = cc CFLAGS = -ansi -pedantic -Wall -Wextra -O3 -g3 -objects = enchive.o chacha.o curve25519-donna.o +objects = enchive.o chacha.o curve25519-donna.o sha256.o enchive: $(objects) $(CC) $(LDFLAGS) -o $@ $(objects) $(LDLIBS) enchive.o: enchive.c chacha.o: chacha.c curve25519-donna.o: curve25519-donna.c +sha256.o: sha256.c clean: rm -f enchive $(objects) diff --git a/enchive.c b/enchive.c index 5924a33..61b3535 100644 --- a/enchive.c +++ b/enchive.c @@ -4,8 +4,9 @@ #include #define OPTPARSE_IMPLEMENTATION -#include "optparse.h" +#include "sha256.h" #include "chacha.h" +#include "optparse.h" int curve25519_donna(u8 *p, const u8 *s, const u8 *b); @@ -57,9 +58,12 @@ static void symmetric_encrypt(FILE *in, FILE *out, u8 *key, u8 *iv) { static u8 buffer[2][64 * 1024]; + u8 sha256[SHA256_BLOCK_SIZE]; + SHA256_CTX hash[1]; chacha_ctx ctx[1]; chacha_keysetup(ctx, key, 256); chacha_ivsetup(ctx, iv); + sha256_init(hash); for (;;) { size_t z = fread(buffer[0], 1, sizeof(buffer[0]), in); @@ -68,10 +72,60 @@ symmetric_encrypt(FILE *in, FILE *out, u8 *key, u8 *iv) fatal("error reading source file"); break; } + sha256_update(hash, buffer[0], z); chacha_encrypt_bytes(ctx, buffer[0], buffer[1], z); if (!fwrite(buffer[1], z, 1, out)) fatal("error writing destination file"); } + + sha256_final(hash, sha256); + if (!fwrite(sha256, SHA224_BLOCK_SIZE, 1, out)) + fatal("error writing checksum to destination file"); + if (fflush(out)) + fatal("error flushing to destination"); +} + +static void +symmetric_decrypt(FILE *in, FILE *out, u8 *key, u8 *iv) +{ + static u8 buffer[2][64 * 1024]; + u8 sha256[SHA256_BLOCK_SIZE]; + SHA256_CTX hash[1]; + chacha_ctx ctx[1]; + chacha_keysetup(ctx, key, 256); + chacha_ivsetup(ctx, iv); + sha256_init(hash); + + /* Always keep SHA224_BLOCK_SIZE bytes in the buffer. */ + if (!(fread(buffer[0], SHA224_BLOCK_SIZE, 1, in))) { + if (ferror(in)) + fatal("error initially reading source file"); + else + fatal("source file missing checksum"); + } + + for (;;) { + u8 *p = buffer[0] + SHA224_BLOCK_SIZE; + size_t z = fread(p, 1, sizeof(buffer[0]) - SHA224_BLOCK_SIZE, in); + if (!z) { + if (ferror(in)) + fatal("error reading source file"); + break; + } + chacha_encrypt_bytes(ctx, buffer[0], buffer[1], z); + sha256_update(hash, buffer[1], z); + if (!fwrite(buffer[1], z, 1, out)) + fatal("error writing destination file"); + + /* Move last SHA224_BLOCK_SIZE bytes to the front. */ + memmove(buffer[0], buffer[0] + z, SHA224_BLOCK_SIZE); + } + if (fflush(out)) + fatal("error flushing to destination"); + + sha256_final(hash, sha256); + if (memcmp(buffer[0], sha256, SHA224_BLOCK_SIZE) != 0) + fatal("checksum mismatch!"); } static const char * @@ -193,7 +247,7 @@ command_extract(struct optparse *options) if (!(fread(epublic, sizeof(epublic), 1, stdin))) fatal("failed to read ephemeral key from archive"); compute_shared(shared, secret, epublic); - symmetric_encrypt(stdin, stdout, shared, iv); + symmetric_decrypt(stdin, stdout, shared, iv); } static void diff --git a/machine.h b/machine.h index a37b640..dc096a1 100644 --- a/machine.h +++ b/machine.h @@ -9,6 +9,7 @@ typedef uint8_t u8; typedef uint16_t u16; typedef uint32_t u32; +typedef uint64_t u64; typedef int32_t s32; typedef int64_t limb; diff --git a/sha256.c b/sha256.c new file mode 100644 index 0000000..368ddf5 --- /dev/null +++ b/sha256.c @@ -0,0 +1,158 @@ +/********************************************************************* +* Filename: sha256.c +* Author: Brad Conte (brad AT bradconte.com) +* Copyright: +* Disclaimer: This code is presented "as is" without any guarantees. +* Details: Implementation of the SHA-256 hashing algorithm. + SHA-256 is one of the three algorithms in the SHA2 + specification. The others, SHA-384 and SHA-512, are not + offered in this implementation. + Algorithm specification can be found here: + * http://csrc.nist.gov/publications/fips/fips180-2/fips180-2withchangenotice.pdf + This implementation uses little endian byte order. +*********************************************************************/ + +/*************************** HEADER FILES ***************************/ +#include +#include +#include "sha256.h" + +/****************************** MACROS ******************************/ +#define ROTLEFT(a,b) (((a) << (b)) | ((a) >> (32-(b)))) +#define ROTRIGHT(a,b) (((a) >> (b)) | ((a) << (32-(b)))) + +#define CH(x,y,z) (((x) & (y)) ^ (~(x) & (z))) +#define MAJ(x,y,z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z))) +#define EP0(x) (ROTRIGHT(x,2) ^ ROTRIGHT(x,13) ^ ROTRIGHT(x,22)) +#define EP1(x) (ROTRIGHT(x,6) ^ ROTRIGHT(x,11) ^ ROTRIGHT(x,25)) +#define SIG0(x) (ROTRIGHT(x,7) ^ ROTRIGHT(x,18) ^ ((x) >> 3)) +#define SIG1(x) (ROTRIGHT(x,17) ^ ROTRIGHT(x,19) ^ ((x) >> 10)) + +/**************************** VARIABLES *****************************/ +static const u32 k[64] = { + 0x428a2f98,0x71374491,0xb5c0fbcf,0xe9b5dba5,0x3956c25b,0x59f111f1,0x923f82a4,0xab1c5ed5, + 0xd807aa98,0x12835b01,0x243185be,0x550c7dc3,0x72be5d74,0x80deb1fe,0x9bdc06a7,0xc19bf174, + 0xe49b69c1,0xefbe4786,0x0fc19dc6,0x240ca1cc,0x2de92c6f,0x4a7484aa,0x5cb0a9dc,0x76f988da, + 0x983e5152,0xa831c66d,0xb00327c8,0xbf597fc7,0xc6e00bf3,0xd5a79147,0x06ca6351,0x14292967, + 0x27b70a85,0x2e1b2138,0x4d2c6dfc,0x53380d13,0x650a7354,0x766a0abb,0x81c2c92e,0x92722c85, + 0xa2bfe8a1,0xa81a664b,0xc24b8b70,0xc76c51a3,0xd192e819,0xd6990624,0xf40e3585,0x106aa070, + 0x19a4c116,0x1e376c08,0x2748774c,0x34b0bcb5,0x391c0cb3,0x4ed8aa4a,0x5b9cca4f,0x682e6ff3, + 0x748f82ee,0x78a5636f,0x84c87814,0x8cc70208,0x90befffa,0xa4506ceb,0xbef9a3f7,0xc67178f2 +}; + +/*********************** FUNCTION DEFINITIONS ***********************/ +void sha256_transform(SHA256_CTX *ctx, const u8 data[]) +{ + u32 a, b, c, d, e, f, g, h, i, j, t1, t2, m[64]; + + for (i = 0, j = 0; i < 16; ++i, j += 4) + m[i] = (data[j] << 24) | (data[j + 1] << 16) | (data[j + 2] << 8) | (data[j + 3]); + for ( ; i < 64; ++i) + m[i] = SIG1(m[i - 2]) + m[i - 7] + SIG0(m[i - 15]) + m[i - 16]; + + a = ctx->state[0]; + b = ctx->state[1]; + c = ctx->state[2]; + d = ctx->state[3]; + e = ctx->state[4]; + f = ctx->state[5]; + g = ctx->state[6]; + h = ctx->state[7]; + + for (i = 0; i < 64; ++i) { + t1 = h + EP1(e) + CH(e,f,g) + k[i] + m[i]; + t2 = EP0(a) + MAJ(a,b,c); + h = g; + g = f; + f = e; + e = d + t1; + d = c; + c = b; + b = a; + a = t1 + t2; + } + + ctx->state[0] += a; + ctx->state[1] += b; + ctx->state[2] += c; + ctx->state[3] += d; + ctx->state[4] += e; + ctx->state[5] += f; + ctx->state[6] += g; + ctx->state[7] += h; +} + +void sha256_init(SHA256_CTX *ctx) +{ + ctx->datalen = 0; + ctx->bitlen = 0; + ctx->state[0] = 0x6a09e667; + ctx->state[1] = 0xbb67ae85; + ctx->state[2] = 0x3c6ef372; + ctx->state[3] = 0xa54ff53a; + ctx->state[4] = 0x510e527f; + ctx->state[5] = 0x9b05688c; + ctx->state[6] = 0x1f83d9ab; + ctx->state[7] = 0x5be0cd19; +} + +void sha256_update(SHA256_CTX *ctx, const u8 data[], size_t len) +{ + u32 i; + + for (i = 0; i < len; ++i) { + ctx->data[ctx->datalen] = data[i]; + ctx->datalen++; + if (ctx->datalen == 64) { + sha256_transform(ctx, ctx->data); + ctx->bitlen += 512; + ctx->datalen = 0; + } + } +} + +void sha256_final(SHA256_CTX *ctx, u8 hash[]) +{ + u32 i; + + i = ctx->datalen; + + /* Pad whatever data is left in the buffer. */ + if (ctx->datalen < 56) { + ctx->data[i++] = 0x80; + while (i < 56) + ctx->data[i++] = 0x00; + } + else { + ctx->data[i++] = 0x80; + while (i < 64) + ctx->data[i++] = 0x00; + sha256_transform(ctx, ctx->data); + memset(ctx->data, 0, 56); + } + + /* Append to the padding the total message's length in bits and transform. */ + ctx->bitlen += ctx->datalen * 8; + ctx->data[63] = ctx->bitlen; + ctx->data[62] = ctx->bitlen >> 8; + ctx->data[61] = ctx->bitlen >> 16; + ctx->data[60] = ctx->bitlen >> 24; + ctx->data[59] = ctx->bitlen >> 32; + ctx->data[58] = ctx->bitlen >> 40; + ctx->data[57] = ctx->bitlen >> 48; + ctx->data[56] = ctx->bitlen >> 56; + sha256_transform(ctx, ctx->data); + + /* Since this implementation uses little endian byte ordering and SHA uses big endian, */ + /* reverse all the bytes when copying the final state to the output hash. */ + for (i = 0; i < 4; ++i) { + hash[i] = (ctx->state[0] >> (24 - i * 8)) & 0x000000ff; + hash[i + 4] = (ctx->state[1] >> (24 - i * 8)) & 0x000000ff; + hash[i + 8] = (ctx->state[2] >> (24 - i * 8)) & 0x000000ff; + hash[i + 12] = (ctx->state[3] >> (24 - i * 8)) & 0x000000ff; + hash[i + 16] = (ctx->state[4] >> (24 - i * 8)) & 0x000000ff; + hash[i + 20] = (ctx->state[5] >> (24 - i * 8)) & 0x000000ff; + hash[i + 24] = (ctx->state[6] >> (24 - i * 8)) & 0x000000ff; + hash[i + 28] = (ctx->state[7] >> (24 - i * 8)) & 0x000000ff; + } +} diff --git a/sha256.h b/sha256.h new file mode 100644 index 0000000..79b3ee6 --- /dev/null +++ b/sha256.h @@ -0,0 +1,33 @@ +/********************************************************************* +* Filename: sha256.h +* Author: Brad Conte (brad AT bradconte.com) +* Copyright: +* Disclaimer: This code is presented "as is" without any guarantees. +* Details: Defines the API for the corresponding SHA1 implementation. +*********************************************************************/ + +#ifndef SHA256_H +#define SHA256_H + +#include +#include "machine.h" + +#define SHA224_BLOCK_SIZE 28 +#define SHA256_BLOCK_SIZE 32 + +typedef unsigned char BYTE; +typedef unsigned int WORD; + +typedef struct { + u8 data[64]; + u32 datalen; + u64 bitlen; + u32 state[8]; +} SHA256_CTX; + +void sha256_init(SHA256_CTX *ctx); +void sha256_update(SHA256_CTX *ctx, const u8 data[], size_t len); +void sha256_final(SHA256_CTX *ctx, u8 hash[]); + +#endif /* SHA256_H */ +