44 lines
1.3 KiB
Go
44 lines
1.3 KiB
Go
// Package mcrypto contains general purpose functionality related to
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// cryptography, notably related to unique identifiers, signing/verifying data,
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// and encrypting/decrypting data
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package mcrypto
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import (
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"bytes"
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"encoding/hex"
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"fmt"
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"io"
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"strconv"
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"strings"
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)
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// Instead of outputing opaque hex garbage, this package opts to add a prefix to
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// the garbage. Each "type" of string returned has its own character which is
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// not found in the hex range (0-9, a-f), and in addition each also has a
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// version character prefixed as well, in case something wants to be changed
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// going forward.
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//
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// We keep the constant prefices here to ensure there's no conflicts across
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// string types in this package.
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const (
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uuidV0 = "0u" // u for uuid
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sigV0 = "0s" // s for signature
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exSigV0 = "0t" // t for time
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uniqueSigV0 = "0q" // q for uni"q"ue
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encryptedV0 = "0n" // n for "n"-crypted, harharhar
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)
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func stripPrefix(s, prefix string) (string, bool) {
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trimmed := strings.TrimPrefix(s, prefix)
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return trimmed, len(trimmed) < len(s)
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}
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func prefixReader(r io.Reader, prefix []byte) io.Reader {
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b := make([]byte, 0, len(prefix)+hex.EncodedLen(strconv.IntSize)+2)
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buf := bytes.NewBuffer(b)
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fmt.Fprintf(buf, "%x\n", len(prefix))
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buf.Write(prefix)
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buf.WriteByte('\n')
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return io.MultiReader(buf, r)
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}
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