143 lines
3.5 KiB
Go
143 lines
3.5 KiB
Go
//go:build !nosas
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// +build !nosas
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package olm
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// #cgo LDFLAGS: -lolm -lstdc++
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// #include <olm/olm.h>
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// #include <olm/sas.h>
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import "C"
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import (
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"crypto/rand"
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"unsafe"
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)
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// SAS stores an Olm Short Authentication String (SAS) object.
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type SAS struct {
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int *C.OlmSAS
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mem []byte
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}
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// NewBlankSAS initializes an empty SAS object.
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func NewBlankSAS() *SAS {
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memory := make([]byte, sasSize())
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return &SAS{
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int: C.olm_sas(unsafe.Pointer(&memory[0])),
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mem: memory,
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}
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}
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// sasSize is the size of a SAS object in bytes.
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func sasSize() uint {
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return uint(C.olm_sas_size())
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}
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// sasRandomLength is the number of random bytes needed to create an SAS object.
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func (sas *SAS) sasRandomLength() uint {
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return uint(C.olm_create_sas_random_length(sas.int))
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}
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// NewSAS creates a new SAS object.
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func NewSAS() *SAS {
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sas := NewBlankSAS()
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random := make([]byte, sas.sasRandomLength()+1)
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_, err := rand.Read(random)
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if err != nil {
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panic(NotEnoughGoRandom)
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}
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r := C.olm_create_sas(
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(*C.OlmSAS)(sas.int),
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unsafe.Pointer(&random[0]),
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C.size_t(len(random)))
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if r == errorVal() {
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panic(sas.lastError())
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} else {
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return sas
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}
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}
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// clear clears the memory used to back an SAS object.
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func (sas *SAS) clear() uint {
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return uint(C.olm_clear_sas(sas.int))
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}
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// lastError returns the most recent error to happen to an SAS object.
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func (sas *SAS) lastError() error {
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return convertError(C.GoString(C.olm_sas_last_error(sas.int)))
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}
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// pubkeyLength is the size of a public key in bytes.
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func (sas *SAS) pubkeyLength() uint {
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return uint(C.olm_sas_pubkey_length((*C.OlmSAS)(sas.int)))
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}
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// GetPubkey gets the public key for the SAS object.
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func (sas *SAS) GetPubkey() []byte {
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pubkey := make([]byte, sas.pubkeyLength())
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r := C.olm_sas_get_pubkey(
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(*C.OlmSAS)(sas.int),
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unsafe.Pointer(&pubkey[0]),
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C.size_t(len(pubkey)))
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if r == errorVal() {
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panic(sas.lastError())
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}
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return pubkey
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}
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// SetTheirKey sets the public key of the other user.
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func (sas *SAS) SetTheirKey(theirKey []byte) error {
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theirKeyCopy := make([]byte, len(theirKey))
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copy(theirKeyCopy, theirKey)
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r := C.olm_sas_set_their_key(
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(*C.OlmSAS)(sas.int),
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unsafe.Pointer(&theirKeyCopy[0]),
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C.size_t(len(theirKeyCopy)))
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if r == errorVal() {
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return sas.lastError()
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}
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return nil
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}
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// GenerateBytes generates bytes to use for the short authentication string.
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func (sas *SAS) GenerateBytes(info []byte, count uint) ([]byte, error) {
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infoCopy := make([]byte, len(info))
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copy(infoCopy, info)
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output := make([]byte, count)
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r := C.olm_sas_generate_bytes(
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(*C.OlmSAS)(sas.int),
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unsafe.Pointer(&infoCopy[0]),
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C.size_t(len(infoCopy)),
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unsafe.Pointer(&output[0]),
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C.size_t(len(output)))
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if r == errorVal() {
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return nil, sas.lastError()
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}
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return output, nil
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}
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// macLength is the size of a message authentication code generated by olm_sas_calculate_mac.
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func (sas *SAS) macLength() uint {
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return uint(C.olm_sas_mac_length((*C.OlmSAS)(sas.int)))
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}
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// CalculateMAC generates a message authentication code (MAC) based on the shared secret.
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func (sas *SAS) CalculateMAC(input []byte, info []byte) ([]byte, error) {
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inputCopy := make([]byte, len(input))
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copy(inputCopy, input)
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infoCopy := make([]byte, len(info))
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copy(infoCopy, info)
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mac := make([]byte, sas.macLength())
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r := C.olm_sas_calculate_mac(
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(*C.OlmSAS)(sas.int),
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unsafe.Pointer(&inputCopy[0]),
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C.size_t(len(inputCopy)),
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unsafe.Pointer(&infoCopy[0]),
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C.size_t(len(infoCopy)),
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unsafe.Pointer(&mac[0]),
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C.size_t(len(mac)))
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if r == errorVal() {
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return nil, sas.lastError()
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}
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return mac, nil
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}
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