50 lines
1.4 KiB
Go
50 lines
1.4 KiB
Go
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// Package zero contains functions to clear data from byte slices and
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// multi-precision integers.
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package zero
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import (
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"math/big"
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)
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// Bytes sets all bytes in the passed slice to zero. This is used to
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// explicitly clear private key material from memory.
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//
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// In general, prefer to use the fixed-sized zeroing functions (Bytea*)
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// when zeroing bytes as they are much more efficient than the variable
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// sized zeroing func Bytes.
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func Bytes(b []byte) {
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z := [32]byte{}
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n := uint(copy(b, z[:]))
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for n < uint(len(b)) {
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copy(b[n:], b[:n])
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n <<= 1
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}
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}
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// Bytea32 clears the 32-byte array by filling it with the zero value.
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// This is used to explicitly clear private key material from memory.
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func Bytea32(b *[32]byte) {
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*b = [32]byte{}
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}
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// Bytea64 clears the 64-byte array by filling it with the zero value.
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// This is used to explicitly clear sensitive material from memory.
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func Bytea64(b *[64]byte) {
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*b = [64]byte{}
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}
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// BigInt sets all bytes in the passed big int to zero and then sets the
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// value to 0. This differs from simply setting the value in that it
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// specifically clears the underlying bytes whereas simply setting the value
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// does not. This is mostly useful to forcefully clear private keys.
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func BigInt(x *big.Int) {
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b := x.Bits()
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z := [16]big.Word{}
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n := uint(copy(b, z[:]))
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for n < uint(len(b)) {
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copy(b[n:], b[:n])
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n <<= 1
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}
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x.SetInt64(0)
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}
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