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stupidgcm: batch C calls in chacha20poly1305_seal

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Go has a high overhead for each C call, so batch
all openssl operations in the new C function chacha20poly1305_seal.

Benchmark results:

internal/speed$ go test -bench BenchmarkStupidXchacha -count 10 > old.txt
internal/speed$ go test -bench BenchmarkStupidXchacha -count 10 > new.txt

internal/speed$ benchstat old.txt new.txt
name             old time/op   new time/op   delta
StupidXchacha-4   8.79µs ± 1%   7.25µs ± 1%  -17.54%  (p=0.000 n=10+10)

name             old speed     new speed     delta
StupidXchacha-4  466MB/s ± 1%  565MB/s ± 1%  +21.27%  (p=0.000 n=10+10)
master
Jakob Unterwurzacher 2 years ago
parent 9e1dd73e55
commit a3f5a8492a
4 changed files with 127 additions and 56 deletions
Show Stats Download Patch File Download Diff File

1
internal/stupidgcm/.gitignore vendored
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@ -0,0 +1 @@
*.o

7
internal/stupidgcm/Makefile
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@ -0,0 +1,7 @@
.PHONY: gcc
gcc:
gcc -Wall -Wextra -Wformat-security -Wconversion -lcrypto -c *.c
.PHONY: format
format:
clang-format --style=WebKit -i *.c

98
internal/stupidgcm/chacha.c
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@ -0,0 +1,98 @@
#include <openssl/evp.h>
#include <stdio.h>
//#cgo pkg-config: libcrypto
extern void panic1(void);
static void panic(const char* const msg)
{
fprintf(stderr, "panic in C code: %s\n", msg);
__builtin_trap();
}
// https://wiki.openssl.org/index.php/EVP_Authenticated_Encryption_and_Decryption#Authenticated_Encryption_using_GCM_mode
int chacha20poly1305_seal(
const unsigned char* const plaintext,
const int plaintextLen,
const unsigned char* const authData,
const int authDataLen,
const unsigned char* const key,
const int keyLen,
const unsigned char* const iv,
const int ivLen,
unsigned char* const ciphertext,
const int ciphertextBufLen)
{
// Create scratch space "context"
EVP_CIPHER_CTX* ctx = EVP_CIPHER_CTX_new();
if (!ctx) {
panic("EVP_CIPHER_CTX_new failed");
}
// Set cipher
if (EVP_EncryptInit_ex(ctx, EVP_chacha20_poly1305(), NULL, NULL, NULL) != 1) {
panic("EVP_EncryptInit_ex set cipher failed");
}
// Check keyLen by trying to set it (fails if keyLen != 32)
if (EVP_CIPHER_CTX_set_key_length(ctx, keyLen) != 1) {
panic("keyLen mismatch");
}
// Set IV length so we do not depend on the default
if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivLen, NULL) != 1) {
panic("EVP_CTRL_AEAD_SET_IVLEN failed");
}
// Set key and IV
if (EVP_EncryptInit_ex(ctx, NULL, NULL, key, iv) != 1) {
panic("EVP_EncryptInit_ex set key & iv failed");
}
// Provide authentication data
int outLen = 0;
if (EVP_EncryptUpdate(ctx, NULL, &outLen, authData, authDataLen) != 1) {
panic("EVP_EncryptUpdate authData failed");
}
if (outLen != authDataLen) {
panic("EVP_EncryptUpdate authData: unexpected length");
}
// Encrypt "plaintext" into "ciphertext"
if (plaintextLen > ciphertextBufLen) {
panic("plaintext overflows output buffer");
}
if (EVP_EncryptUpdate(ctx, ciphertext, &outLen, plaintext, plaintextLen) != 1) {
panic("EVP_EncryptUpdate ciphertext failed");
}
if (outLen != plaintextLen) {
panic("EVP_EncryptUpdate ciphertext: unexpected length");
}
int ciphertextLen = outLen;
// Finalise encryption
// Normally ciphertext bytes may be written at this stage, but this does not occur in GCM mode
if (EVP_EncryptFinal_ex(ctx, ciphertext + plaintextLen, &outLen) != 1) {
panic("EVP_EncryptFinal_ex failed");
}
if (outLen != 0) {
panic("EVP_EncryptFinal_ex: unexpected length");
}
// We only support 16-byte tags
const int tagLen = 16;
// Get MAC tag and append it to the ciphertext
if (ciphertextLen + tagLen > ciphertextBufLen) {
panic("tag overflows output buffer");
}
if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, tagLen, ciphertext + plaintextLen) != 1) {
panic("EVP_CTRL_AEAD_GET_TAG failed");
}
ciphertextLen += tagLen;
// Free scratch space
EVP_CIPHER_CTX_free(ctx);
return ciphertextLen;
}

77
internal/stupidgcm/stupidchacha.go
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@ -2,10 +2,6 @@
package stupidgcm
// #include <openssl/evp.h>
// #cgo pkg-config: libcrypto
import "C"
import (
"crypto/cipher"
"fmt"
@ -15,6 +11,17 @@ import (
"golang.org/x/crypto/chacha20poly1305"
)
/*
#include <openssl/evp.h>
#cgo pkg-config: libcrypto
int chacha20poly1305_seal(const unsigned char * const plaintext, const int plaintextLen,
const unsigned char * const authData, const int authDataLen,
const unsigned char * const key, const int keyLen,
const unsigned char * const iv, const int ivLen,
unsigned char * const ciphertext, const int ciphertextBufLen);
*/
import "C"
type stupidChacha20poly1305 struct {
key [chacha20poly1305.KeySize]byte
wiped bool
@ -68,58 +75,16 @@ func (g *stupidChacha20poly1305) Seal(dst, iv, in, authData []byte) []byte {
buf = make([]byte, outLen)
}
// https://wiki.openssl.org/index.php/EVP_Authenticated_Encryption_and_Decryption#Authenticated_Encryption_using_GCM_mode
// Create scratch space "context"
ctx := C.EVP_CIPHER_CTX_new()
if ctx == nil {
log.Panic("EVP_CIPHER_CTX_new failed")
}
// Set cipher
if C.EVP_EncryptInit_ex(ctx, C.EVP_chacha20_poly1305(), nil, nil, nil) != 1 {
log.Panic("EVP_EncryptInit_ex I failed")
}
// Set key and IV
if C.EVP_EncryptInit_ex(ctx, nil, nil, (*C.uchar)(&g.key[0]), (*C.uchar)(&iv[0])) != 1 {
log.Panic("EVP_EncryptInit_ex II failed")
}
// Provide authentication data
var resultLen C.int
if C.EVP_EncryptUpdate(ctx, nil, &resultLen, (*C.uchar)(&authData[0]), C.int(len(authData))) != 1 {
log.Panic("EVP_EncryptUpdate authData failed")
}
if int(resultLen) != len(authData) {
log.Panicf("Unexpected length %d", resultLen)
}
// Encrypt "in" into "buf"
if C.EVP_EncryptUpdate(ctx, (*C.uchar)(&buf[0]), &resultLen, (*C.uchar)(&in[0]), C.int(len(in))) != 1 {
log.Panic("EVP_EncryptUpdate failed")
}
if int(resultLen) != len(in) {
log.Panicf("Unexpected length %d", resultLen)
}
// Finalise encryption
// Because GCM is a stream encryption, this will not write out any data.
dummy := make([]byte, 16)
if C.EVP_EncryptFinal_ex(ctx, (*C.uchar)(&dummy[0]), &resultLen) != 1 {
log.Panic("EVP_EncryptFinal_ex failed")
}
if resultLen != 0 {
log.Panicf("Unexpected length %d", resultLen)
}
// Get MAC tag and append it to the ciphertext in "buf"
if C.EVP_CIPHER_CTX_ctrl(ctx, C.EVP_CTRL_AEAD_GET_TAG, tagLen, (unsafe.Pointer)(&buf[len(in)])) != 1 {
log.Panic("EVP_CIPHER_CTX_ctrl EVP_CTRL_AEAD_GET_TAG failed")
}
// Free scratch space
C.EVP_CIPHER_CTX_free(ctx)
C.chacha20poly1305_seal((*C.uchar)(&in[0]),
C.int(len(in)),
(*C.uchar)(&authData[0]),
C.int(len(authData)),
(*C.uchar)(&g.key[0]),
C.int(len(g.key)),
(*C.uchar)(&iv[0]),
C.int(len(iv)),
(*C.uchar)(&buf[0]),
C.int(len(buf)))
if inplace {
return dst[:len(dst)+outLen]

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