55 lines
1.4 KiB
Go
55 lines
1.4 KiB
Go
// +build !without_openssl
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package stupidgcm
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import (
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"crypto/cipher"
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"log"
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"golang.org/x/crypto/chacha20poly1305"
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)
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/*
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#include <openssl/evp.h>
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*/
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import "C"
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type stupidChacha20poly1305 struct {
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stupidAEADCommon
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}
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// Verify that we satisfy the cipher.AEAD interface
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var _ cipher.AEAD = &stupidChacha20poly1305{}
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// _EVP_chacha20_poly1305 caches C.EVP_chacha20_poly1305() to avoid the Cgo call
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// overhead for each instantiation of NewChacha20poly1305.
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var _EVP_chacha20_poly1305 *C.EVP_CIPHER
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func init() {
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_EVP_chacha20_poly1305 = C.EVP_chacha20_poly1305()
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}
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// NewChacha20poly1305 returns a new instance of the OpenSSL ChaCha20-Poly1305 AEAD
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// cipher ( https://www.openssl.org/docs/man1.1.1/man3/EVP_chacha20_poly1305.html ).
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//
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// gocryptfs only uses ChaCha20-Poly1305 as a building block for OpenSSL
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// XChaCha20-Poly1305. This function is hot because it gets called once for each
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// block by XChaCha20-Poly1305.
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//
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// Only 32-bytes keys and 12-byte IVs are supported.
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func NewChacha20poly1305(key []byte) *stupidChacha20poly1305 {
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if len(key) != chacha20poly1305.KeySize {
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log.Panicf("Only %d-byte keys are supported, you passed %d bytes", chacha20poly1305.KeySize, len(key))
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}
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// private copy
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key2 := make([]byte, chacha20poly1305.KeySize)
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copy(key2, key)
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return &stupidChacha20poly1305{
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stupidAEADCommon{
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key: key2,
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openSSLEVPCipher: _EVP_chacha20_poly1305,
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nonceSize: chacha20poly1305.NonceSize,
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},
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}
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}
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