miegl/glorytun
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Do not use the shared secret as AES key directly

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angt
2015-10-31 22:03:47 +01:00
parent 0aeab9a33b
commit 1b3c23889a
1 changed files with 13 additions and 1 deletions
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14
glorytun.c
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@@ -451,6 +451,8 @@ static void gt_setup_crypto (struct crypto_ctx *ctx, int fd, int listener)
unsigned char public_w[crypto_scalarmult_SCALARBYTES]; unsigned char public_w[crypto_scalarmult_SCALARBYTES];
unsigned char public_r[crypto_scalarmult_SCALARBYTES]; unsigned char public_r[crypto_scalarmult_SCALARBYTES];
unsigned char key[crypto_aead_aes256gcm_KEYBYTES];
randombytes_buf(secret, sizeof(secret)); randombytes_buf(secret, sizeof(secret));
crypto_scalarmult_base(public_w, secret); crypto_scalarmult_base(public_w, secret);
@@ -463,7 +465,15 @@ static void gt_setup_crypto (struct crypto_ctx *ctx, int fd, int listener)
fd_write_all(fd, public_w, sizeof(public_w)); fd_write_all(fd, public_w, sizeof(public_w));
crypto_scalarmult(shared, secret, public_r); crypto_scalarmult(shared, secret, public_r);
crypto_aead_aes256gcm_beforenm(&ctx->state, shared);
crypto_generichash_state state;
crypto_generichash_init(&state, NULL, 0, sizeof(key));
crypto_generichash_update(&state, shared, sizeof(shared));
crypto_generichash_update(&state, listener?public_w:public_r, sizeof(public_w));
crypto_generichash_update(&state, listener?public_r:public_w, sizeof(public_w));
crypto_generichash_final(&state, key, sizeof(key));
crypto_aead_aes256gcm_beforenm(&ctx->state, key);
sodium_memzero(secret, sizeof(secret)); sodium_memzero(secret, sizeof(secret));
sodium_memzero(shared, sizeof(shared)); sodium_memzero(shared, sizeof(shared));
@@ -471,6 +481,8 @@ static void gt_setup_crypto (struct crypto_ctx *ctx, int fd, int listener)
sodium_memzero(public_w, sizeof(public_w)); sodium_memzero(public_w, sizeof(public_w));
sodium_memzero(public_r, sizeof(public_r)); sodium_memzero(public_r, sizeof(public_r));
sodium_memzero(key, sizeof(key));
randombytes_buf(ctx->nonce_w, sizeof(ctx->nonce_w)); randombytes_buf(ctx->nonce_w, sizeof(ctx->nonce_w));
fd_write_all(fd, ctx->nonce_w, sizeof(ctx->nonce_w)); fd_write_all(fd, ctx->nonce_w, sizeof(ctx->nonce_w));