Update dependencies

vendor/github.com/hdevalence/ed25519consensus/batch.go

@@ -0,0 +1,151 @@
+package ed25519consensus
+
+import (
+	"crypto/ed25519"
+	"crypto/rand"
+	"crypto/sha512"
+
+	"filippo.io/edwards25519"
+)
+
+// BatchVerifier accumulates batch entries with Add, before performing batch
+// verification with Verify.
+type BatchVerifier struct {
+	entries []entry
+}
+
+// entry represents a batch entry with the public key, signature and scalar
+// which the caller wants to verify.
+type entry struct {
+	good      bool // good is true if the Add inputs were valid
+	pubkey    [ed25519.PublicKeySize]byte
+	signature [ed25519.SignatureSize]byte
+	digest    [64]byte
+}
+
+// NewBatchVerifier creates an empty BatchVerifier.
+func NewBatchVerifier() BatchVerifier {
+	return BatchVerifier{
+		entries: []entry{},
+	}
+}
+
+// NewPreallocatedBatchVerifier creates a new BatchVerifier with
+// a preallocated capacity. If you know the size of the batch you plan
+// to create ahead of time, this can prevent needless memory copies.
+func NewPreallocatedBatchVerifier(size int) BatchVerifier {
+	return BatchVerifier{
+		entries: make([]entry, 0, size),
+	}
+}
+
+// Add adds a (public key, message, sig) triple to the current batch. It retains
+// no reference to the inputs.
+func (v *BatchVerifier) Add(publicKey ed25519.PublicKey, message, sig []byte) {
+	// Compute the challenge upfront to store it in the fixed-size entry
+	// structure that can get allocated on the caller stack and avoid heap
+	// allocations. Also, avoid holding any reference to the arguments.
+
+	v.entries = append(v.entries, entry{})
+	e := &v.entries[len(v.entries)-1]
+
+	if len(publicKey) != ed25519.PublicKeySize || len(sig) != ed25519.SignatureSize {
+		return
+	}
+
+	h := sha512.New()
+	h.Write(sig[:32])
+	h.Write(publicKey)
+	h.Write(message)
+	h.Sum(e.digest[:0])
+
+	copy(e.pubkey[:], publicKey)
+	copy(e.signature[:], sig)
+
+	e.good = true
+}
+
+// Verify checks all entries in the current batch, returning true if all entries
+// are valid and false if any one entry is invalid.
+//
+// If a failure arises it is unknown which entry failed, the caller must verify
+// each entry individually.
+//
+// Calling Verify on an empty batch returns false.
+func (v *BatchVerifier) Verify() bool {
+	vl := len(v.entries)
+	// Abort early on an empty batch, which probably indicates a bug
+	if vl == 0 {
+		return false
+	}
+
+	// The batch verification equation is
+	//
+	// [-sum(z_i * s_i)]B + sum([z_i]R_i) + sum([z_i * k_i]A_i) = 0.
+	// where for each signature i,
+	// - A_i is the verification key;
+	// - R_i is the signature's R value;
+	// - s_i is the signature's s value;
+	// - k_i is the hash of the message and other data;
+	// - z_i is a random 128-bit Scalar.
+	svals := make([]edwards25519.Scalar, 1+vl+vl)
+	scalars := make([]*edwards25519.Scalar, 1+vl+vl)
+
+	// Populate scalars variable with concrete scalars to reduce heap allocation
+	for i := range scalars {
+		scalars[i] = &svals[i]
+	}
+
+	Bcoeff := scalars[0]
+	Rcoeffs := scalars[1 : 1+vl]
+	Acoeffs := scalars[1+vl:]
+
+	pvals := make([]edwards25519.Point, 1+vl+vl)
+	points := make([]*edwards25519.Point, 1+vl+vl)
+	for i := range points {
+		points[i] = &pvals[i]
+	}
+	B := points[0]
+	Rs := points[1 : 1+vl]
+	As := points[1+vl:]
+
+	buf := make([]byte, 32)
+	B.Set(edwards25519.NewGeneratorPoint())
+	for i, entry := range v.entries {
+		if !entry.good {
+			return false
+		}
+
+		if _, err := Rs[i].SetBytes(entry.signature[:32]); err != nil {
+			return false
+		}
+
+		if _, err := As[i].SetBytes(entry.pubkey[:]); err != nil {
+			return false
+		}
+
+		if _, err := rand.Read(buf[:16]); err != nil {
+			return false
+		}
+		if _, err := Rcoeffs[i].SetCanonicalBytes(buf); err != nil {
+			return false
+		}
+
+		s, err := new(edwards25519.Scalar).SetCanonicalBytes(entry.signature[32:])
+		if err != nil {
+			return false
+		}
+		Bcoeff.MultiplyAdd(Rcoeffs[i], s, Bcoeff)
+
+		k, err := new(edwards25519.Scalar).SetUniformBytes(entry.digest[:])
+		if err != nil {
+			return false
+		}
+		Acoeffs[i].Multiply(Rcoeffs[i], k)
+	}
+	Bcoeff.Negate(Bcoeff) // this term is subtracted in the summation
+
+	check := new(edwards25519.Point).VarTimeMultiScalarMult(scalars, points)
+	check.MultByCofactor(check)
+	return check.Equal(edwards25519.NewIdentityPoint()) == 1
+}