diff --git a/src/crypto/internal/boring/sha.go b/src/crypto/internal/boring/sha.go
index b7843674a57..c9772aa6f1c 100644
--- a/src/crypto/internal/boring/sha.go
+++ b/src/crypto/internal/boring/sha.go
@@ -145,6 +145,20 @@ func (h *sha1Hash) Write(p []byte) (int, error) {
 	return len(p), nil
 }
 
+func (h *sha1Hash) WriteString(s string) (int, error) {
+	if len(s) > 0 && C._goboringcrypto_SHA1_Update(h.noescapeCtx(), unsafe.Pointer(unsafe.StringData(s)), C.size_t(len(s))) == 0 {
+		panic("boringcrypto: SHA1_Update failed")
+	}
+	return len(s), nil
+}
+
+func (h *sha1Hash) WriteByte(c byte) error {
+	if C._goboringcrypto_SHA1_Update(h.noescapeCtx(), unsafe.Pointer(&c), 1) == 0 {
+		panic("boringcrypto: SHA1_Update failed")
+	}
+	return nil
+}
+
 func (h0 *sha1Hash) sum(dst []byte) []byte {
 	h := *h0 // make copy so future Write+Sum is valid
 	if C._goboringcrypto_SHA1_Final((*C.uint8_t)(noescape(unsafe.Pointer(&h.out[0]))), h.noescapeCtx()) == 0 {
diff --git a/src/crypto/sha1/sha1.go b/src/crypto/sha1/sha1.go
index 43ab72a4854..19f17678829 100644
--- a/src/crypto/sha1/sha1.go
+++ b/src/crypto/sha1/sha1.go
@@ -120,18 +120,10 @@ func (d *digest) Size() int { return Size }
 func (d *digest) BlockSize() int { return BlockSize }
 
 func (d *digest) Write(p []byte) (nn int, err error) {
-	boringUnreachable()
 	nn = len(p)
 	d.len += uint64(nn)
-	if d.nx > 0 {
-		n := copy(d.x[d.nx:], p)
-		d.nx += n
-		if d.nx == chunk {
-			block(d, d.x[:])
-			d.nx = 0
-		}
-		p = p[n:]
-	}
+	n := fillChunk(d, p)
+	p = p[n:]
 	if len(p) >= chunk {
 		n := len(p) &^ (chunk - 1)
 		block(d, p[:n])
@@ -143,6 +135,55 @@ func (d *digest) Write(p []byte) (nn int, err error) {
 	return
 }
 
+func (d *digest) WriteString(s string) (nn int, err error) {
+	nn = len(s)
+	d.len += uint64(nn)
+	n := fillChunk(d, s)
+
+	// This duplicates the code in Write, except that it calls
+	// blockString rather than block. It would be nicer to pass
+	// in a func, but as of this writing (Go 1.20) that causes
+	// memory allocations that we want to avoid.
+
+	s = s[n:]
+	if len(s) >= chunk {
+		n := len(s) &^ (chunk - 1)
+		blockString(d, s[:n])
+		s = s[n:]
+	}
+	if len(s) > 0 {
+		d.nx = copy(d.x[:], s)
+	}
+	return
+}
+
+// fillChunk fills the remainder of the current chunk, if any.
+func fillChunk[S []byte | string](d *digest, p S) int {
+	boringUnreachable()
+	if d.nx == 0 {
+		return 0
+	}
+	n := copy(d.x[d.nx:], p)
+	d.nx += n
+	if d.nx == chunk {
+		block(d, d.x[:])
+		d.nx = 0
+	}
+	return n
+}
+
+func (d *digest) WriteByte(c byte) error {
+	boringUnreachable()
+	d.len++
+	d.x[d.nx] = c
+	d.nx++
+	if d.nx == chunk {
+		block(d, d.x[:])
+		d.nx = 0
+	}
+	return nil
+}
+
 func (d *digest) Sum(in []byte) []byte {
 	boringUnreachable()
 	// Make a copy of d so that caller can keep writing and summing.
diff --git a/src/crypto/sha1/sha1_test.go b/src/crypto/sha1/sha1_test.go
index 85ed1260915..2f0980adaa7 100644
--- a/src/crypto/sha1/sha1_test.go
+++ b/src/crypto/sha1/sha1_test.go
@@ -92,6 +92,14 @@ func TestGolden(t *testing.T) {
 			}
 			c.Reset()
 		}
+		bw := c.(io.ByteWriter)
+		for i := 0; i < len(g.in); i++ {
+			bw.WriteByte(g.in[i])
+		}
+		s = fmt.Sprintf("%x", c.Sum(nil))
+		if s != g.out {
+			t.Errorf("sha1[WriteByte](%s) = %s want %s", g.in, s, g.out)
+		}
 	}
 }
 
@@ -221,7 +229,8 @@ func TestAllocations(t *testing.T) {
 	if boring.Enabled {
 		t.Skip("BoringCrypto doesn't allocate the same way as stdlib")
 	}
-	in := []byte("hello, world!")
+	const ins = "hello, world!"
+	in := []byte(ins)
 	out := make([]byte, 0, Size)
 	h := New()
 	n := int(testing.AllocsPerRun(10, func() {
@@ -232,6 +241,28 @@ func TestAllocations(t *testing.T) {
 	if n > 0 {
 		t.Errorf("allocs = %d, want 0", n)
 	}
+
+	sw := h.(io.StringWriter)
+	n = int(testing.AllocsPerRun(10, func() {
+		h.Reset()
+		sw.WriteString(ins)
+		out = h.Sum(out[:0])
+	}))
+	if n > 0 {
+		t.Errorf("string allocs = %d, want 0", n)
+	}
+
+	bw := h.(io.ByteWriter)
+	n = int(testing.AllocsPerRun(10, func() {
+		h.Reset()
+		for _, b := range in {
+			bw.WriteByte(b)
+		}
+		out = h.Sum(out[:0])
+	}))
+	if n > 0 {
+		t.Errorf("byte allocs = %d, want 0", n)
+	}
 }
 
 var bench = New()
diff --git a/src/crypto/sha1/sha1block.go b/src/crypto/sha1/sha1block.go
index 1c1a7c5f31c..0b332859dfc 100644
--- a/src/crypto/sha1/sha1block.go
+++ b/src/crypto/sha1/sha1block.go
@@ -17,7 +17,7 @@ const (
 
 // blockGeneric is a portable, pure Go version of the SHA-1 block step.
 // It's used by sha1block_generic.go and tests.
-func blockGeneric(dig *digest, p []byte) {
+func blockGeneric[S []byte | string](dig *digest, p S) {
 	var w [16]uint32
 
 	h0, h1, h2, h3, h4 := dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4]
diff --git a/src/crypto/sha1/sha1block_386.s b/src/crypto/sha1/sha1block_386.s
index 34d023d424c..9421b4ebd69 100644
--- a/src/crypto/sha1/sha1block_386.s
+++ b/src/crypto/sha1/sha1block_386.s
@@ -98,11 +98,11 @@
 	FUNC4(a, b, c, d, e); \
 	MIX(a, b, c, d, e, 0xCA62C1D6)
 
-// func block(dig *digest, p []byte)
-TEXT ·block(SB),NOSPLIT,$92-16
+// func doBlock(dig *digest, p *byte, n int)
+TEXT ·doBlock(SB),NOSPLIT,$92-12
 	MOVL	dig+0(FP),	BP
 	MOVL	p+4(FP),	SI
-	MOVL	p_len+8(FP),	DX
+	MOVL	n+8(FP),	DX
 	SHRL	$6,		DX
 	SHLL	$6,		DX
 
diff --git a/src/crypto/sha1/sha1block_amd64.go b/src/crypto/sha1/sha1block_amd64.go
index 039813d7dc3..528d65dd71b 100644
--- a/src/crypto/sha1/sha1block_amd64.go
+++ b/src/crypto/sha1/sha1block_amd64.go
@@ -4,19 +4,22 @@
 
 package sha1
 
-import "internal/cpu"
+import (
+	"internal/cpu"
+	"unsafe"
+)
 
 //go:noescape
-func blockAVX2(dig *digest, p []byte)
+func blockAVX2(dig *digest, p *byte, n int)
 
 //go:noescape
-func blockAMD64(dig *digest, p []byte)
+func blockAMD64(dig *digest, p *byte, n int)
 
 var useAVX2 = cpu.X86.HasAVX2 && cpu.X86.HasBMI1 && cpu.X86.HasBMI2
 
 func block(dig *digest, p []byte) {
 	if useAVX2 && len(p) >= 256 {
-		// blockAVX2 calculates sha1 for 2 block per iteration
+		// blockAVX2 calculates sha1 for 2 blocks per iteration
 		// it also interleaves precalculation for next block.
 		// So it may read up-to 192 bytes past end of p
 		// We may add checks inside blockAVX2, but this will
@@ -26,9 +29,25 @@ func block(dig *digest, p []byte) {
 		if safeLen%128 != 0 {
 			safeLen -= 64
 		}
-		blockAVX2(dig, p[:safeLen])
-		blockAMD64(dig, p[safeLen:])
+		blockAVX2(dig, unsafe.SliceData(p), safeLen)
+		pRem := p[safeLen:]
+		blockAMD64(dig, unsafe.SliceData(pRem), len(pRem))
 	} else {
-		blockAMD64(dig, p)
+		blockAMD64(dig, unsafe.SliceData(p), len(p))
+	}
+}
+
+// blockString is a duplicate of block that takes a string.
+func blockString(dig *digest, s string) {
+	if useAVX2 && len(s) >= 256 {
+		safeLen := len(s) - 128
+		if safeLen%128 != 0 {
+			safeLen -= 64
+		}
+		blockAVX2(dig, unsafe.StringData(s), safeLen)
+		sRem := s[safeLen:]
+		blockAMD64(dig, unsafe.StringData(sRem), len(sRem))
+	} else {
+		blockAMD64(dig, unsafe.StringData(s), len(s))
 	}
 }
diff --git a/src/crypto/sha1/sha1block_amd64.s b/src/crypto/sha1/sha1block_amd64.s
index 9bdf24cf49f..23b47dac906 100644
--- a/src/crypto/sha1/sha1block_amd64.s
+++ b/src/crypto/sha1/sha1block_amd64.s
@@ -96,10 +96,10 @@
 	FUNC4(a, b, c, d, e); \
 	MIX(a, b, c, d, e, 0xCA62C1D6)
 
-TEXT ·blockAMD64(SB),NOSPLIT,$64-32
+TEXT ·blockAMD64(SB),NOSPLIT,$64-24
 	MOVQ	dig+0(FP),	BP
-	MOVQ	p_base+8(FP),	SI
-	MOVQ	p_len+16(FP),	DX
+	MOVQ	p+8(FP),	SI
+	MOVQ	n+16(FP),	DX
 	SHRQ	$6,		DX
 	SHLQ	$6,		DX
 
@@ -1430,11 +1430,11 @@ begin: \
 
 
 
-TEXT ·blockAVX2(SB),$1408-32
+TEXT ·blockAVX2(SB),$1408-24
 
 	MOVQ	dig+0(FP),	DI
-	MOVQ	p_base+8(FP),	SI
-	MOVQ	p_len+16(FP),	DX
+	MOVQ	p+8(FP),	SI
+	MOVQ	n+16(FP),	DX
 	SHRQ	$6,		DX
 	SHLQ	$6,		DX
 
diff --git a/src/crypto/sha1/sha1block_arm.s b/src/crypto/sha1/sha1block_arm.s
index 2236533ab4d..db651db3625 100644
--- a/src/crypto/sha1/sha1block_arm.s
+++ b/src/crypto/sha1/sha1block_arm.s
@@ -38,11 +38,10 @@
 #define Rctr	R12	// loop counter
 #define Rw	R14		// point to w buffer
 
-// func block(dig *digest, p []byte)
+// func doBlock(dig *digest, p *byte, n int)
 // 0(FP) is *digest
 // 4(FP) is p.array (struct Slice)
 // 8(FP) is p.len
-//12(FP) is p.cap
 //
 // Stack frame
 #define p_end	end-4(SP)		// pointer to the end of data
@@ -136,10 +135,10 @@
 	MIX(Ra, Rb, Rc, Rd, Re)
 
 
-// func block(dig *digest, p []byte)
-TEXT	·block(SB), 0, $352-16
+// func doBlock(dig *digest, p *byte, n int)
+TEXT	·doBlock(SB), 0, $352-12
 	MOVW	p+4(FP), Rdata	// pointer to the data
-	MOVW	p_len+8(FP), Rt0	// number of bytes
+	MOVW	n+8(FP), Rt0	// number of bytes
 	ADD	Rdata, Rt0
 	MOVW	Rt0, p_end	// pointer to end of data
 
diff --git a/src/crypto/sha1/sha1block_arm64.go b/src/crypto/sha1/sha1block_arm64.go
index 08d3df0000e..846c88226f0 100644
--- a/src/crypto/sha1/sha1block_arm64.go
+++ b/src/crypto/sha1/sha1block_arm64.go
@@ -4,7 +4,10 @@
 
 package sha1
 
-import "internal/cpu"
+import (
+	"internal/cpu"
+	"unsafe"
+)
 
 var k = []uint32{
 	0x5A827999,
@@ -14,13 +17,22 @@ var k = []uint32{
 }
 
 //go:noescape
-func sha1block(h []uint32, p []byte, k []uint32)
+func sha1block(h []uint32, p *byte, n int, k []uint32)
 
 func block(dig *digest, p []byte) {
 	if !cpu.ARM64.HasSHA1 {
 		blockGeneric(dig, p)
 	} else {
 		h := dig.h[:]
-		sha1block(h, p, k)
+		sha1block(h, unsafe.SliceData(p), len(p), k)
+	}
+}
+
+func blockString(dig *digest, s string) {
+	if !cpu.ARM64.HasSHA1 {
+		blockGeneric(dig, s)
+	} else {
+		h := dig.h[:]
+		sha1block(h, unsafe.StringData(s), len(s), k)
 	}
 }
diff --git a/src/crypto/sha1/sha1block_arm64.s b/src/crypto/sha1/sha1block_arm64.s
index d56838464dd..e5e32437350 100644
--- a/src/crypto/sha1/sha1block_arm64.s
+++ b/src/crypto/sha1/sha1block_arm64.s
@@ -19,12 +19,12 @@
 	SHA1H	V3, V1 \
 	VMOV	V2.B16, V3.B16
 
-// func sha1block(h []uint32, p []byte, k []uint32)
+// func sha1block(h []uint32, p *byte, n int, k []uint32)
 TEXT ·sha1block(SB),NOSPLIT,$0
 	MOVD	h_base+0(FP), R0                             // hash value first address
-	MOVD	p_base+24(FP), R1                            // message first address
-	MOVD	k_base+48(FP), R2                            // k constants first address
-	MOVD	p_len+32(FP), R3                             // message length
+	MOVD	p+24(FP), R1                                 // message first address
+	MOVD	k_base+40(FP), R2                            // k constants first address
+	MOVD	n+32(FP), R3                                 // message length
 	VLD1.P	16(R0), [V0.S4]
 	FMOVS	(R0), F20
 	SUB	$16, R0, R0
diff --git a/src/crypto/sha1/sha1block_decl.go b/src/crypto/sha1/sha1block_decl.go
index 8e20401c14c..9ef8709637c 100644
--- a/src/crypto/sha1/sha1block_decl.go
+++ b/src/crypto/sha1/sha1block_decl.go
@@ -6,5 +6,15 @@
 
 package sha1
 
+import "unsafe"
+
 //go:noescape
-func block(dig *digest, p []byte)
+func doBlock(dig *digest, p *byte, n int)
+
+func block(dig *digest, p []byte) {
+	doBlock(dig, unsafe.SliceData(p), len(p))
+}
+
+func blockString(dig *digest, s string) {
+	doBlock(dig, unsafe.StringData(s), len(s))
+}
diff --git a/src/crypto/sha1/sha1block_generic.go b/src/crypto/sha1/sha1block_generic.go
index ba35155d0b9..4eb489f01a1 100644
--- a/src/crypto/sha1/sha1block_generic.go
+++ b/src/crypto/sha1/sha1block_generic.go
@@ -9,3 +9,7 @@ package sha1
 func block(dig *digest, p []byte) {
 	blockGeneric(dig, p)
 }
+
+func blockString(dig *digest, s string) {
+	blockGeneric(dig, s)
+}
diff --git a/src/crypto/sha1/sha1block_s390x.go b/src/crypto/sha1/sha1block_s390x.go
index 446bf5d36e5..06c972d3af9 100644
--- a/src/crypto/sha1/sha1block_s390x.go
+++ b/src/crypto/sha1/sha1block_s390x.go
@@ -4,6 +4,13 @@
 
 package sha1
 
-import "internal/cpu"
+import (
+	"internal/cpu"
+	"unsafe"
+)
 
 var useAsm = cpu.S390X.HasSHA1
+
+func doBlockGeneric(dig *digest, p *byte, n int) {
+	blockGeneric(dig, unsafe.String(p, n))
+}
diff --git a/src/crypto/sha1/sha1block_s390x.s b/src/crypto/sha1/sha1block_s390x.s
index 6ba6883cc38..3d082342ff1 100644
--- a/src/crypto/sha1/sha1block_s390x.s
+++ b/src/crypto/sha1/sha1block_s390x.s
@@ -4,10 +4,10 @@
 
 #include "textflag.h"
 
-// func block(dig *digest, p []byte)
-TEXT ·block(SB), NOSPLIT|NOFRAME, $0-32
+// func doBlock(dig *digest, p *byte, n int)
+TEXT ·doBlock(SB), NOSPLIT|NOFRAME, $0-24
 	MOVBZ  ·useAsm(SB), R4
-	LMG    dig+0(FP), R1, R3            // R2 = &p[0], R3 = len(p)
+	LMG    dig+0(FP), R1, R3            // R2 = p, R3 = n
 	MOVBZ  $1, R0                       // SHA-1 function code
 	CMPBEQ R4, $0, generic
 
@@ -17,4 +17,4 @@ loop:
 	RET
 
 generic:
-	BR ·blockGeneric(SB)
+	BR ·doBlockGeneric(SB)