diff --git a/shamir/README.md b/shamir/README.md
new file mode 100644
index 000000000..f73198baa
--- /dev/null
+++ b/shamir/README.md
@@ -0,0 +1 @@
+Forked from [Vault](https://github.com/hashicorp/vault/tree/master/shamir)
diff --git a/shamir/shamir.go b/shamir/shamir.go
new file mode 100644
index 000000000..d6f5137e5
--- /dev/null
+++ b/shamir/shamir.go
@@ -0,0 +1,260 @@
+package shamir
+
+import (
+	"crypto/rand"
+	"crypto/subtle"
+	"fmt"
+	mathrand "math/rand"
+	"time"
+)
+
+const (
+	// ShareOverhead is the byte size overhead of each share
+	// when using Split on a secret. This is caused by appending
+	// a one byte tag to the share.
+	ShareOverhead = 1
+)
+
+// polynomial represents a polynomial of arbitrary degree
+type polynomial struct {
+	coefficients []uint8
+}
+
+// makePolynomial constructs a random polynomial of the given
+// degree but with the provided intercept value.
+func makePolynomial(intercept, degree uint8) (polynomial, error) {
+	// Create a wrapper
+	p := polynomial{
+		coefficients: make([]byte, degree+1),
+	}
+
+	// Ensure the intercept is set
+	p.coefficients[0] = intercept
+
+	// Assign random co-efficients to the polynomial
+	if _, err := rand.Read(p.coefficients[1:]); err != nil {
+		return p, err
+	}
+
+	return p, nil
+}
+
+// evaluate returns the value of the polynomial for the given x
+func (p *polynomial) evaluate(x uint8) uint8 {
+	// Special case the origin
+	if x == 0 {
+		return p.coefficients[0]
+	}
+
+	// Compute the polynomial value using Horner's method.
+	degree := len(p.coefficients) - 1
+	out := p.coefficients[degree]
+	for i := degree - 1; i >= 0; i-- {
+		coeff := p.coefficients[i]
+		out = add(mult(out, x), coeff)
+	}
+	return out
+}
+
+// interpolatePolynomial takes N sample points and returns
+// the value at a given x using a lagrange interpolation.
+func interpolatePolynomial(x_samples, y_samples []uint8, x uint8) uint8 {
+	limit := len(x_samples)
+	var result, basis uint8
+	for i := 0; i < limit; i++ {
+		basis = 1
+		for j := 0; j < limit; j++ {
+			if i == j {
+				continue
+			}
+			num := add(x, x_samples[j])
+			denom := add(x_samples[i], x_samples[j])
+			term := div(num, denom)
+			basis = mult(basis, term)
+		}
+		group := mult(y_samples[i], basis)
+		result = add(result, group)
+	}
+	return result
+}
+
+// div divides two numbers in GF(2^8)
+func div(a, b uint8) uint8 {
+	if b == 0 {
+		// leaks some timing information but we don't care anyways as this
+		// should never happen, hence the panic
+		panic("divide by zero")
+	}
+
+	var goodVal, zero uint8
+	log_a := logTable[a]
+	log_b := logTable[b]
+	diff := (int(log_a) - int(log_b)) % 255
+	if diff < 0 {
+		diff += 255
+	}
+
+	ret := expTable[diff]
+
+	// Ensure we return zero if a is zero but aren't subject to timing attacks
+	goodVal = ret
+
+	if subtle.ConstantTimeByteEq(a, 0) == 1 {
+		ret = zero
+	} else {
+		ret = goodVal
+	}
+
+	return ret
+}
+
+// mult multiplies two numbers in GF(2^8)
+func mult(a, b uint8) (out uint8) {
+	var goodVal, zero uint8
+	log_a := logTable[a]
+	log_b := logTable[b]
+	sum := (int(log_a) + int(log_b)) % 255
+
+	ret := expTable[sum]
+
+	// Ensure we return zero if either a or be are zero but aren't subject to
+	// timing attacks
+	goodVal = ret
+
+	if subtle.ConstantTimeByteEq(a, 0) == 1 {
+		ret = zero
+	} else {
+		ret = goodVal
+	}
+
+	if subtle.ConstantTimeByteEq(b, 0) == 1 {
+		ret = zero
+	} else {
+		// This operation does not do anything logically useful. It
+		// only ensures a constant number of assignments to thwart
+		// timing attacks.
+		goodVal = zero
+	}
+
+	return ret
+}
+
+// add combines two numbers in GF(2^8)
+// This can also be used for subtraction since it is symmetric.
+func add(a, b uint8) uint8 {
+	return a ^ b
+}
+
+// Split takes an arbitrarily long secret and generates a `parts`
+// number of shares, `threshold` of which are required to reconstruct
+// the secret. The parts and threshold must be at least 2, and less
+// than 256. The returned shares are each one byte longer than the secret
+// as they attach a tag used to reconstruct the secret.
+func Split(secret []byte, parts, threshold int) ([][]byte, error) {
+	// Sanity check the input
+	if parts < threshold {
+		return nil, fmt.Errorf("parts cannot be less than threshold")
+	}
+	if parts > 255 {
+		return nil, fmt.Errorf("parts cannot exceed 255")
+	}
+	if threshold < 2 {
+		return nil, fmt.Errorf("threshold must be at least 2")
+	}
+	if threshold > 255 {
+		return nil, fmt.Errorf("threshold cannot exceed 255")
+	}
+	if len(secret) == 0 {
+		return nil, fmt.Errorf("cannot split an empty secret")
+	}
+
+	// Generate random list of x coordinates
+	mathrand.Seed(time.Now().UnixNano())
+	xCoordinates := mathrand.Perm(255)
+
+	// Allocate the output array, initialize the final byte
+	// of the output with the offset. The representation of each
+	// output is {y1, y2, .., yN, x}.
+	out := make([][]byte, parts)
+	for idx := range out {
+		out[idx] = make([]byte, len(secret)+1)
+		out[idx][len(secret)] = uint8(xCoordinates[idx]) + 1
+	}
+
+	// Construct a random polynomial for each byte of the secret.
+	// Because we are using a field of size 256, we can only represent
+	// a single byte as the intercept of the polynomial, so we must
+	// use a new polynomial for each byte.
+	for idx, val := range secret {
+		p, err := makePolynomial(val, uint8(threshold-1))
+		if err != nil {
+			return nil, fmt.Errorf("failed to generate polynomial: %v", err)
+		}
+
+		// Generate a `parts` number of (x,y) pairs
+		// We cheat by encoding the x value once as the final index,
+		// so that it only needs to be stored once.
+		for i := 0; i < parts; i++ {
+			x := uint8(xCoordinates[i]) + 1
+			y := p.evaluate(x)
+			out[i][idx] = y
+		}
+	}
+
+	// Return the encoded secrets
+	return out, nil
+}
+
+// Combine is used to reverse a Split and reconstruct a secret
+// once a `threshold` number of parts are available.
+func Combine(parts [][]byte) ([]byte, error) {
+	// Verify enough parts provided
+	if len(parts) < 2 {
+		return nil, fmt.Errorf("less than two parts cannot be used to reconstruct the secret")
+	}
+
+	// Verify the parts are all the same length
+	firstPartLen := len(parts[0])
+	if firstPartLen < 2 {
+		return nil, fmt.Errorf("parts must be at least two bytes")
+	}
+	for i := 1; i < len(parts); i++ {
+		if len(parts[i]) != firstPartLen {
+			return nil, fmt.Errorf("all parts must be the same length")
+		}
+	}
+
+	// Create a buffer to store the reconstructed secret
+	secret := make([]byte, firstPartLen-1)
+
+	// Buffer to store the samples
+	x_samples := make([]uint8, len(parts))
+	y_samples := make([]uint8, len(parts))
+
+	// Set the x value for each sample and ensure no x_sample values are the same,
+	// otherwise div() can be unhappy
+	checkMap := map[byte]bool{}
+	for i, part := range parts {
+		samp := part[firstPartLen-1]
+		if exists := checkMap[samp]; exists {
+			return nil, fmt.Errorf("duplicate part detected")
+		}
+		checkMap[samp] = true
+		x_samples[i] = samp
+	}
+
+	// Reconstruct each byte
+	for idx := range secret {
+		// Set the y value for each sample
+		for i, part := range parts {
+			y_samples[i] = part[idx]
+		}
+
+		// Interpolte the polynomial and compute the value at 0
+		val := interpolatePolynomial(x_samples, y_samples, 0)
+
+		// Evaluate the 0th value to get the intercept
+		secret[idx] = val
+	}
+	return secret, nil
+}
diff --git a/shamir/shamir_test.go b/shamir/shamir_test.go
new file mode 100644
index 000000000..09f90d5fc
--- /dev/null
+++ b/shamir/shamir_test.go
@@ -0,0 +1,198 @@
+package shamir
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestSplit_invalid(t *testing.T) {
+	secret := []byte("test")
+
+	if _, err := Split(secret, 0, 0); err == nil {
+		t.Fatalf("expect error")
+	}
+
+	if _, err := Split(secret, 2, 3); err == nil {
+		t.Fatalf("expect error")
+	}
+
+	if _, err := Split(secret, 1000, 3); err == nil {
+		t.Fatalf("expect error")
+	}
+
+	if _, err := Split(secret, 10, 1); err == nil {
+		t.Fatalf("expect error")
+	}
+
+	if _, err := Split(nil, 3, 2); err == nil {
+		t.Fatalf("expect error")
+	}
+}
+
+func TestSplit(t *testing.T) {
+	secret := []byte("test")
+
+	out, err := Split(secret, 5, 3)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	if len(out) != 5 {
+		t.Fatalf("bad: %v", out)
+	}
+
+	for _, share := range out {
+		if len(share) != len(secret)+1 {
+			t.Fatalf("bad: %v", out)
+		}
+	}
+}
+
+func TestCombine_invalid(t *testing.T) {
+	// Not enough parts
+	if _, err := Combine(nil); err == nil {
+		t.Fatalf("should err")
+	}
+
+	// Mis-match in length
+	parts := [][]byte{
+		[]byte("foo"),
+		[]byte("ba"),
+	}
+	if _, err := Combine(parts); err == nil {
+		t.Fatalf("should err")
+	}
+
+	//Too short
+	parts = [][]byte{
+		[]byte("f"),
+		[]byte("b"),
+	}
+	if _, err := Combine(parts); err == nil {
+		t.Fatalf("should err")
+	}
+
+	parts = [][]byte{
+		[]byte("foo"),
+		[]byte("foo"),
+	}
+	if _, err := Combine(parts); err == nil {
+		t.Fatalf("should err")
+	}
+}
+
+func TestCombine(t *testing.T) {
+	secret := []byte("test")
+
+	out, err := Split(secret, 5, 3)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	// There is 5*4*3 possible choices,
+	// we will just brute force try them all
+	for i := 0; i < 5; i++ {
+		for j := 0; j < 5; j++ {
+			if j == i {
+				continue
+			}
+			for k := 0; k < 5; k++ {
+				if k == i || k == j {
+					continue
+				}
+				parts := [][]byte{out[i], out[j], out[k]}
+				recomb, err := Combine(parts)
+				if err != nil {
+					t.Fatalf("err: %v", err)
+				}
+
+				if !bytes.Equal(recomb, secret) {
+					t.Errorf("parts: (i:%d, j:%d, k:%d) %v", i, j, k, parts)
+					t.Fatalf("bad: %v %v", recomb, secret)
+				}
+			}
+		}
+	}
+}
+
+func TestField_Add(t *testing.T) {
+	if out := add(16, 16); out != 0 {
+		t.Fatalf("Bad: %v 16", out)
+	}
+
+	if out := add(3, 4); out != 7 {
+		t.Fatalf("Bad: %v 7", out)
+	}
+}
+
+func TestField_Mult(t *testing.T) {
+	if out := mult(3, 7); out != 9 {
+		t.Fatalf("Bad: %v 9", out)
+	}
+
+	if out := mult(3, 0); out != 0 {
+		t.Fatalf("Bad: %v 0", out)
+	}
+
+	if out := mult(0, 3); out != 0 {
+		t.Fatalf("Bad: %v 0", out)
+	}
+}
+
+func TestField_Divide(t *testing.T) {
+	if out := div(0, 7); out != 0 {
+		t.Fatalf("Bad: %v 0", out)
+	}
+
+	if out := div(3, 3); out != 1 {
+		t.Fatalf("Bad: %v 1", out)
+	}
+
+	if out := div(6, 3); out != 2 {
+		t.Fatalf("Bad: %v 2", out)
+	}
+}
+
+func TestPolynomial_Random(t *testing.T) {
+	p, err := makePolynomial(42, 2)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	if p.coefficients[0] != 42 {
+		t.Fatalf("bad: %v", p.coefficients)
+	}
+}
+
+func TestPolynomial_Eval(t *testing.T) {
+	p, err := makePolynomial(42, 1)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	if out := p.evaluate(0); out != 42 {
+		t.Fatalf("bad: %v", out)
+	}
+
+	out := p.evaluate(1)
+	exp := add(42, mult(1, p.coefficients[1]))
+	if out != exp {
+		t.Fatalf("bad: %v %v %v", out, exp, p.coefficients)
+	}
+}
+
+func TestInterpolate_Rand(t *testing.T) {
+	for i := 0; i < 256; i++ {
+		p, err := makePolynomial(uint8(i), 2)
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+
+		x_vals := []uint8{1, 2, 3}
+		y_vals := []uint8{p.evaluate(1), p.evaluate(2), p.evaluate(3)}
+		out := interpolatePolynomial(x_vals, y_vals, 0)
+		if out != uint8(i) {
+			t.Fatalf("Bad: %v %d", out, i)
+		}
+	}
+}
diff --git a/shamir/tables.go b/shamir/tables.go
new file mode 100644
index 000000000..76c245e79
--- /dev/null
+++ b/shamir/tables.go
@@ -0,0 +1,77 @@
+package shamir
+
+// Tables taken from http://www.samiam.org/galois.html
+// They use 0xe5 (229) as the generator
+
+var (
+	// logTable provides the log(X)/log(g) at each index X
+	logTable = [256]uint8{
+		0x00, 0xff, 0xc8, 0x08, 0x91, 0x10, 0xd0, 0x36,
+		0x5a, 0x3e, 0xd8, 0x43, 0x99, 0x77, 0xfe, 0x18,
+		0x23, 0x20, 0x07, 0x70, 0xa1, 0x6c, 0x0c, 0x7f,
+		0x62, 0x8b, 0x40, 0x46, 0xc7, 0x4b, 0xe0, 0x0e,
+		0xeb, 0x16, 0xe8, 0xad, 0xcf, 0xcd, 0x39, 0x53,
+		0x6a, 0x27, 0x35, 0x93, 0xd4, 0x4e, 0x48, 0xc3,
+		0x2b, 0x79, 0x54, 0x28, 0x09, 0x78, 0x0f, 0x21,
+		0x90, 0x87, 0x14, 0x2a, 0xa9, 0x9c, 0xd6, 0x74,
+		0xb4, 0x7c, 0xde, 0xed, 0xb1, 0x86, 0x76, 0xa4,
+		0x98, 0xe2, 0x96, 0x8f, 0x02, 0x32, 0x1c, 0xc1,
+		0x33, 0xee, 0xef, 0x81, 0xfd, 0x30, 0x5c, 0x13,
+		0x9d, 0x29, 0x17, 0xc4, 0x11, 0x44, 0x8c, 0x80,
+		0xf3, 0x73, 0x42, 0x1e, 0x1d, 0xb5, 0xf0, 0x12,
+		0xd1, 0x5b, 0x41, 0xa2, 0xd7, 0x2c, 0xe9, 0xd5,
+		0x59, 0xcb, 0x50, 0xa8, 0xdc, 0xfc, 0xf2, 0x56,
+		0x72, 0xa6, 0x65, 0x2f, 0x9f, 0x9b, 0x3d, 0xba,
+		0x7d, 0xc2, 0x45, 0x82, 0xa7, 0x57, 0xb6, 0xa3,
+		0x7a, 0x75, 0x4f, 0xae, 0x3f, 0x37, 0x6d, 0x47,
+		0x61, 0xbe, 0xab, 0xd3, 0x5f, 0xb0, 0x58, 0xaf,
+		0xca, 0x5e, 0xfa, 0x85, 0xe4, 0x4d, 0x8a, 0x05,
+		0xfb, 0x60, 0xb7, 0x7b, 0xb8, 0x26, 0x4a, 0x67,
+		0xc6, 0x1a, 0xf8, 0x69, 0x25, 0xb3, 0xdb, 0xbd,
+		0x66, 0xdd, 0xf1, 0xd2, 0xdf, 0x03, 0x8d, 0x34,
+		0xd9, 0x92, 0x0d, 0x63, 0x55, 0xaa, 0x49, 0xec,
+		0xbc, 0x95, 0x3c, 0x84, 0x0b, 0xf5, 0xe6, 0xe7,
+		0xe5, 0xac, 0x7e, 0x6e, 0xb9, 0xf9, 0xda, 0x8e,
+		0x9a, 0xc9, 0x24, 0xe1, 0x0a, 0x15, 0x6b, 0x3a,
+		0xa0, 0x51, 0xf4, 0xea, 0xb2, 0x97, 0x9e, 0x5d,
+		0x22, 0x88, 0x94, 0xce, 0x19, 0x01, 0x71, 0x4c,
+		0xa5, 0xe3, 0xc5, 0x31, 0xbb, 0xcc, 0x1f, 0x2d,
+		0x3b, 0x52, 0x6f, 0xf6, 0x2e, 0x89, 0xf7, 0xc0,
+		0x68, 0x1b, 0x64, 0x04, 0x06, 0xbf, 0x83, 0x38}
+
+	// expTable provides the anti-log or exponentiation value
+	// for the equivalent index
+	expTable = [256]uint8{
+		0x01, 0xe5, 0x4c, 0xb5, 0xfb, 0x9f, 0xfc, 0x12,
+		0x03, 0x34, 0xd4, 0xc4, 0x16, 0xba, 0x1f, 0x36,
+		0x05, 0x5c, 0x67, 0x57, 0x3a, 0xd5, 0x21, 0x5a,
+		0x0f, 0xe4, 0xa9, 0xf9, 0x4e, 0x64, 0x63, 0xee,
+		0x11, 0x37, 0xe0, 0x10, 0xd2, 0xac, 0xa5, 0x29,
+		0x33, 0x59, 0x3b, 0x30, 0x6d, 0xef, 0xf4, 0x7b,
+		0x55, 0xeb, 0x4d, 0x50, 0xb7, 0x2a, 0x07, 0x8d,
+		0xff, 0x26, 0xd7, 0xf0, 0xc2, 0x7e, 0x09, 0x8c,
+		0x1a, 0x6a, 0x62, 0x0b, 0x5d, 0x82, 0x1b, 0x8f,
+		0x2e, 0xbe, 0xa6, 0x1d, 0xe7, 0x9d, 0x2d, 0x8a,
+		0x72, 0xd9, 0xf1, 0x27, 0x32, 0xbc, 0x77, 0x85,
+		0x96, 0x70, 0x08, 0x69, 0x56, 0xdf, 0x99, 0x94,
+		0xa1, 0x90, 0x18, 0xbb, 0xfa, 0x7a, 0xb0, 0xa7,
+		0xf8, 0xab, 0x28, 0xd6, 0x15, 0x8e, 0xcb, 0xf2,
+		0x13, 0xe6, 0x78, 0x61, 0x3f, 0x89, 0x46, 0x0d,
+		0x35, 0x31, 0x88, 0xa3, 0x41, 0x80, 0xca, 0x17,
+		0x5f, 0x53, 0x83, 0xfe, 0xc3, 0x9b, 0x45, 0x39,
+		0xe1, 0xf5, 0x9e, 0x19, 0x5e, 0xb6, 0xcf, 0x4b,
+		0x38, 0x04, 0xb9, 0x2b, 0xe2, 0xc1, 0x4a, 0xdd,
+		0x48, 0x0c, 0xd0, 0x7d, 0x3d, 0x58, 0xde, 0x7c,
+		0xd8, 0x14, 0x6b, 0x87, 0x47, 0xe8, 0x79, 0x84,
+		0x73, 0x3c, 0xbd, 0x92, 0xc9, 0x23, 0x8b, 0x97,
+		0x95, 0x44, 0xdc, 0xad, 0x40, 0x65, 0x86, 0xa2,
+		0xa4, 0xcc, 0x7f, 0xec, 0xc0, 0xaf, 0x91, 0xfd,
+		0xf7, 0x4f, 0x81, 0x2f, 0x5b, 0xea, 0xa8, 0x1c,
+		0x02, 0xd1, 0x98, 0x71, 0xed, 0x25, 0xe3, 0x24,
+		0x06, 0x68, 0xb3, 0x93, 0x2c, 0x6f, 0x3e, 0x6c,
+		0x0a, 0xb8, 0xce, 0xae, 0x74, 0xb1, 0x42, 0xb4,
+		0x1e, 0xd3, 0x49, 0xe9, 0x9c, 0xc8, 0xc6, 0xc7,
+		0x22, 0x6e, 0xdb, 0x20, 0xbf, 0x43, 0x51, 0x52,
+		0x66, 0xb2, 0x76, 0x60, 0xda, 0xc5, 0xf3, 0xf6,
+		0xaa, 0xcd, 0x9a, 0xa0, 0x75, 0x54, 0x0e, 0x01}
+)
diff --git a/shamir/tables_test.go b/shamir/tables_test.go
new file mode 100644
index 000000000..81aa983b1
--- /dev/null
+++ b/shamir/tables_test.go
@@ -0,0 +1,13 @@
+package shamir
+
+import "testing"
+
+func TestTables(t *testing.T) {
+	for i := 1; i < 256; i++ {
+		logV := logTable[i]
+		expV := expTable[logV]
+		if expV != uint8(i) {
+			t.Fatalf("bad: %d log: %d exp: %d", i, logV, expV)
+		}
+	}
+}
diff --git a/sops.go b/sops.go
index b5ff3c7b3..dfd3fb027 100644
--- a/sops.go
+++ b/sops.go
@@ -43,7 +43,7 @@ import (
 	"strings"
 	"time"
 
-	"github.com/hashicorp/vault/shamir"
+	"go.mozilla.org/sops/shamir"
 	"go.mozilla.org/sops/kms"
 	"go.mozilla.org/sops/pgp"
 )