Initial Swift API for PEM format (#453)

* Initial Swift API for PEM format

* Created PEM keys from OpenSSL for unit tests

* Updated readme

.swiftlint.yml

@@ -132,7 +132,19 @@ included: # paths to include during linting. `--path` is ignored if present.
   - Sources
   - Tests
 excluded: # paths to ignore during linting. Takes precedence over `included`.
+  - Sources/**/ArraySliceBigint.swift
+  - Sources/**/ASN1.swift
+  - Sources/**/ASN1BitString.swift
+  - Sources/**/ASN1Boolean.swift
+  - Sources/**/ASN1Identifier.swift
+  - Sources/**/ASN1Integer.swift
+  - Sources/**/ASN1OctetString.swift
+  - Sources/**/ASN1Strings.swift
   - Sources/**/Digest.swift
+  - Sources/**/ECDSASignature.swift
+  - Sources/**/GeneralizedTime.swift
+  - Sources/**/PEMDocument.swift
+  - Sources/**/PKCS8PrivateKey.swift
   - Sources/**/PrettyBytes.swift
   - Sources/**/RNG_boring.swift
   - Sources/**/SecureBytes.swift

README.md

@@ -20,7 +20,7 @@ Long-term goals are:
 This repository primarily uses Swift package manager as its build tool, so we recommend using that as well. Xcode comes with [built-in support](https://developer.apple.com/documentation/xcode/adding-package-dependencies-to-your-app) for Swift packages. From the menu bar, goto: `File > Add Packages...` If you manage packages via a `Package.swift` file, simply add `secp256k1.swift` as a dependencies' clause in your Swift manifest:
 
 ```swift
-.package(name: "secp256k1.swift", url: "https://github.com/GigaBitcoin/secp256k1.swift.git", exact: "0.13.0"),
+.package(name: "secp256k1.swift", url: "https://github.com/GigaBitcoin/secp256k1.swift.git", exact: "0.15.0"),
 ```
 
 Include `secp256k1` as a dependency for your executable target:
@@ -136,7 +136,7 @@ let publicKey = try! secp256k1.Recovery.PublicKey(messageData, signature: recove
 let signature = try! recoverySignature.normalize
 ```
 
-# Combine Public Keys
+## Combine Public Keys
 
 ```swift
 let privateKey = try! secp256k1.Signing.PrivateKey()
@@ -146,6 +146,21 @@ let publicKey = try! secp256k1.Signing.PrivateKey().public
 publicKey.combine([privateKey.publicKey], format: .uncompressed)
 ```
 
+## PEM Key Format
+
+```swift
+let privateKeyString = """
+-----BEGIN EC PRIVATE KEY-----
+MHQCAQEEIBXwHPDpec6b07GeLbnwetT0dvWzp0nV3MR+4pPKXIc7oAcGBSuBBAAK
+oUQDQgAEt2uDn+2GqqYs/fmkBr5+rCQ3oiFSIJMAcjHIrTDS6HEELgguOatmFBOp
+2wU4P2TAl/0Ihiq+nMkrAIV69m2W8g==
+-----END EC PRIVATE KEY-----
+"""
+
+// Import keys generated from OpenSSL
+let privateKey = try! secp256k1.Signing.PrivateKey(pemRepresentation: privateKeyString)
+```
+
 
 # Danger
 These APIs should not be considered stable and may change at any time.

Sources/secp256k1/ASN1/ASN1.swift

@@ -0,0 +1 @@
+../../../Submodules/swift-crypto/Sources/Crypto/ASN1/ASN1.swift

Sources/secp256k1/ASN1/Basic ASN1 Types/ASN1Any.swift

@@ -0,0 +1 @@
+../../../../Submodules/swift-crypto/Sources/Crypto/ASN1/Basic ASN1 Types/ASN1Any.swift

Sources/secp256k1/ASN1/Basic ASN1 Types/ASN1BitString.swift

@@ -0,0 +1 @@
+../../../../Submodules/swift-crypto/Sources/Crypto/ASN1/Basic ASN1 Types/ASN1BitString.swift

Sources/secp256k1/ASN1/Basic ASN1 Types/ASN1Boolean.swift

@@ -0,0 +1 @@
+../../../../Submodules/swift-crypto/Sources/Crypto/ASN1/Basic ASN1 Types/ASN1Boolean.swift

Sources/secp256k1/ASN1/Basic ASN1 Types/ASN1Identifier.swift

@@ -0,0 +1 @@
+../../../../Submodules/swift-crypto/Sources/Crypto/ASN1/Basic ASN1 Types/ASN1Identifier.swift

Sources/secp256k1/ASN1/Basic ASN1 Types/ASN1Integer.swift

@@ -0,0 +1 @@
+../../../../Submodules/swift-crypto/Sources/Crypto/ASN1/Basic ASN1 Types/ASN1Integer.swift

Sources/secp256k1/ASN1/Basic ASN1 Types/ASN1Null.swift

@@ -0,0 +1 @@
+../../../../Submodules/swift-crypto/Sources/Crypto/ASN1/Basic ASN1 Types/ASN1Null.swift

Sources/secp256k1/ASN1/Basic ASN1 Types/ASN1OctetString.swift

@@ -0,0 +1 @@
+../../../../Submodules/swift-crypto/Sources/Crypto/ASN1/Basic ASN1 Types/ASN1OctetString.swift

Sources/secp256k1/ASN1/Basic ASN1 Types/ASN1Strings.swift

@@ -0,0 +1 @@
+../../../../Submodules/swift-crypto/Sources/Crypto/ASN1/Basic ASN1 Types/ASN1Strings.swift

Sources/secp256k1/ASN1/Basic ASN1 Types/ArraySliceBigint.swift

@@ -0,0 +1 @@
+../../../../Submodules/swift-crypto/Sources/Crypto/ASN1/Basic ASN1 Types/ArraySliceBigint.swift

Sources/secp256k1/ASN1/Basic ASN1 Types/GeneralizedTime.swift

@@ -0,0 +1 @@
+../../../../Submodules/swift-crypto/Sources/Crypto/ASN1/Basic ASN1 Types/GeneralizedTime.swift

Sources/secp256k1/ASN1/Basic ASN1 Types/ObjectIdentifier.swift

@@ -0,0 +1 @@
+../../../zkp/ASN1/Basic ASN1 Types/ObjectIdentifier.swift

Sources/secp256k1/ASN1/ECDSASignature.swift

@@ -0,0 +1 @@
+../../../Submodules/swift-crypto/Sources/Crypto/ASN1/ECDSASignature.swift

Sources/secp256k1/ASN1/PEMDocument.swift

@@ -0,0 +1 @@
+../../../Submodules/swift-crypto/Sources/Crypto/ASN1/PEMDocument.swift

Sources/secp256k1/ASN1/PKCS8PrivateKey.swift

@@ -0,0 +1 @@
+../../../Submodules/swift-crypto/Sources/Crypto/ASN1/PKCS8PrivateKey.swift

Sources/secp256k1/ASN1/SEC1PrivateKey.swift

@@ -0,0 +1 @@
+../../zkp/ASN1/SEC1PrivateKey.swift

Sources/secp256k1/ASN1/SubjectPublicKeyInfo.swift

@@ -0,0 +1 @@
+../../zkp/ASN1/SubjectPublicKeyInfo.swift

Sources/secp256k1/CryptoKitErrors.swift

@@ -0,0 +1 @@
+../../Submodules/swift-crypto/Sources/Crypto/CryptoKitErrors.swift

Sources/zkp/ASN1/ASN1.swift

@@ -0,0 +1 @@
+../../../Submodules/swift-crypto/Sources/Crypto/ASN1/ASN1.swift

Sources/zkp/ASN1/Basic ASN1 Types/ASN1Any.swift

@@ -0,0 +1 @@
+../../../../Submodules/swift-crypto/Sources/Crypto/ASN1/Basic ASN1 Types/ASN1Any.swift

Sources/zkp/ASN1/Basic ASN1 Types/ASN1BitString.swift

@@ -0,0 +1 @@
+../../../../Submodules/swift-crypto/Sources/Crypto/ASN1/Basic ASN1 Types/ASN1BitString.swift

Sources/zkp/ASN1/Basic ASN1 Types/ASN1Boolean.swift

@@ -0,0 +1 @@
+../../../../Submodules/swift-crypto/Sources/Crypto/ASN1/Basic ASN1 Types/ASN1Boolean.swift

Sources/zkp/ASN1/Basic ASN1 Types/ASN1Identifier.swift

@@ -0,0 +1 @@
+../../../../Submodules/swift-crypto/Sources/Crypto/ASN1/Basic ASN1 Types/ASN1Identifier.swift

Sources/zkp/ASN1/Basic ASN1 Types/ASN1Integer.swift

@@ -0,0 +1 @@
+../../../../Submodules/swift-crypto/Sources/Crypto/ASN1/Basic ASN1 Types/ASN1Integer.swift

Sources/zkp/ASN1/Basic ASN1 Types/ASN1Null.swift

@@ -0,0 +1 @@
+../../../../Submodules/swift-crypto/Sources/Crypto/ASN1/Basic ASN1 Types/ASN1Null.swift

Sources/zkp/ASN1/Basic ASN1 Types/ASN1OctetString.swift

@@ -0,0 +1 @@
+../../../../Submodules/swift-crypto/Sources/Crypto/ASN1/Basic ASN1 Types/ASN1OctetString.swift

Sources/zkp/ASN1/Basic ASN1 Types/ASN1Strings.swift

@@ -0,0 +1 @@
+../../../../Submodules/swift-crypto/Sources/Crypto/ASN1/Basic ASN1 Types/ASN1Strings.swift

Sources/zkp/ASN1/Basic ASN1 Types/ArraySliceBigint.swift

@@ -0,0 +1 @@
+../../../../Submodules/swift-crypto/Sources/Crypto/ASN1/Basic ASN1 Types/ArraySliceBigint.swift

Sources/zkp/ASN1/Basic ASN1 Types/GeneralizedTime.swift

@@ -0,0 +1 @@
+../../../../Submodules/swift-crypto/Sources/Crypto/ASN1/Basic ASN1 Types/GeneralizedTime.swift

Sources/zkp/ASN1/Basic ASN1 Types/ObjectIdentifier.swift

@@ -0,0 +1,231 @@
+//
+//  ObjectIdentifier.swift
+//  GigaBitcoin/secp256k1.swift
+//
+//  Modifications Copyright (c) 2023 GigaBitcoin LLC
+//  Distributed under the MIT software license
+//
+//  See the accompanying file LICENSE for information
+//
+//
+//  NOTICE: THIS FILE HAS BEEN MODIFIED BY GigaBitcoin LLC
+//  UNDER COMPLIANCE WITH THE APACHE 2.0 LICENSE FROM THE
+//  ORIGINAL WORK OF THE COMPANY Apple Inc.
+//
+//  THE FOLLOWING IS THE COPYRIGHT OF THE ORIGINAL DOCUMENT:
+//
+//
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the SwiftCrypto open source project
+//
+// Copyright (c) 2019-2020 Apple Inc. and the SwiftCrypto project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.md for the list of SwiftCrypto project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+#if CRYPTO_IN_SWIFTPM && !CRYPTO_IN_SWIFTPM_FORCE_BUILD_API
+    @_exported import CryptoKit
+#else
+    import Foundation
+
+    extension ASN1 {
+        /// An Object Identifier is a representation of some kind of object: really any kind of object.
+        ///
+        /// It represents a node in an OID hierarchy, and is usually represented as an ordered sequence of numbers.
+        ///
+        /// We mostly don't care about the semantics of the thing, we just care about being able to store and compare them.
+        struct ASN1ObjectIdentifier: ASN1ImplicitlyTaggable {
+            static var defaultIdentifier: ASN1.ASN1Identifier {
+                .objectIdentifier
+            }
+
+            private var oidComponents: [UInt]
+
+            init(asn1Encoded node: ASN1.ASN1Node, withIdentifier identifier: ASN1.ASN1Identifier) throws {
+                guard node.identifier == identifier else {
+                    throw CryptoKitASN1Error.unexpectedFieldType
+                }
+
+                guard case var .primitive(content) = node.content else {
+                    preconditionFailure("ASN.1 parser generated primitive node with constructed content")
+                }
+
+                // We have to parse the content. From the spec:
+                //
+                // > Each subidentifier is represented as a series of (one or more) octets. Bit 8 of each octet indicates whether it
+                // > is the last in the series: bit 8 of the last octet is zero, bit 8 of each preceding octet is one. Bits 7 to 1 of
+                // > the octets in the series collectively encode the subidentifier. Conceptually, these groups of bits are concatenated
+                // > to form an unsigned binary number whose most significant bit is bit 7 of the first octet and whose least significant
+                // > bit is bit 1 of the last octet. The subidentifier shall be encoded in the fewest possible octets[...].
+                // >
+                // > The number of subidentifiers (N) shall be one less than the number of object identifier components in the object identifier
+                // > value being encoded.
+                // >
+                // > The numerical value of the first subidentifier is derived from the values of the first _two_ object identifier components
+                // > in the object identifier value being encoded, using the formula:
+                // >
+                // >  (X*40) + Y
+                // >
+                // > where X is the value of the first object identifier component and Y is the value of the second object identifier component.
+                //
+                // Yeah, this is a bit bananas, but basically there are only 3 first OID components (0, 1, 2) and there are no more than 39 children
+                // of nodes 0 or 1. In my view this is too clever by half, but the ITU.T didn't ask for my opinion when they were coming up with this
+                // scheme, likely because I was in middle school at the time.
+                var subcomponents = [UInt]()
+                while content.count > 0 {
+                    try subcomponents.append(content.readOIDSubidentifier())
+                }
+
+                guard subcomponents.count >= 2 else {
+                    throw CryptoKitASN1Error.invalidObjectIdentifier
+                }
+
+                // Now we need to expand the subcomponents out. This means we need to undo the step above. The first component will be in the range 0..<40
+                // when the first oidComponent is 0, 40..<80 when the first oidComponent is 1, and 80+ when the first oidComponent is 2.
+                var oidComponents = [UInt]()
+                oidComponents.reserveCapacity(subcomponents.count + 1)
+
+                switch subcomponents.first! {
+                case ..<40:
+                    oidComponents.append(0)
+                    oidComponents.append(subcomponents.first!)
+
+                case 40..<80:
+                    oidComponents.append(1)
+                    oidComponents.append(subcomponents.first! - 40)
+
+                default:
+                    oidComponents.append(2)
+                    oidComponents.append(subcomponents.first! - 80)
+                }
+
+                oidComponents.append(contentsOf: subcomponents.dropFirst())
+
+                self.oidComponents = oidComponents
+            }
+
+            func serialize(into coder: inout ASN1.Serializer, withIdentifier identifier: ASN1.ASN1Identifier) throws {
+                coder.appendPrimitiveNode(identifier: identifier) { bytes in
+                    var components = self.oidComponents[...]
+                    guard let firstComponent = components.popFirst(), let secondComponent = components.popFirst() else {
+                        preconditionFailure("Invalid number of OID components: must be at least two!")
+                    }
+
+                    let serializedFirstComponent = (firstComponent * 40) + secondComponent
+                    Self.writeOIDSubidentifier(serializedFirstComponent, into: &bytes)
+
+                    while let component = components.popFirst() {
+                        Self.writeOIDSubidentifier(component, into: &bytes)
+                    }
+                }
+            }
+
+            private static func writeOIDSubidentifier(_ identifier: UInt, into array: inout [UInt8]) {
+                // An OID subidentifier is written as an integer over 7-bit bytes, where the last byte has the top bit unset.
+                // The first thing we need is to know how many bits we need to write
+                let bitsToWrite = UInt.bitWidth - identifier.leadingZeroBitCount
+                let bytesToWrite = (bitsToWrite + 6) / 7
+
+                guard bytesToWrite > 0 else {
+                    // Just a zero.
+                    array.append(0)
+                    return
+                }
+
+                for byteNumber in (1..<bytesToWrite).reversed() {
+                    let shift = byteNumber * 7
+                    let byte = UInt8((identifier >> shift) & 0x7F) | 0x80
+                    array.append(byte)
+                }
+
+                // Last byte to append here, we must unset the top bit.
+                let byte = UInt8(identifier & 0x7F)
+                array.append(byte)
+            }
+        }
+    }
+
+    extension ASN1.ASN1ObjectIdentifier: Hashable {}
+
+    extension ASN1.ASN1ObjectIdentifier: ExpressibleByArrayLiteral {
+        init(arrayLiteral elements: UInt...) {
+            self.oidComponents = elements
+        }
+    }
+
+    extension ASN1.ASN1ObjectIdentifier {
+        enum NamedCurves {
+            static let secp256k1: ASN1.ASN1ObjectIdentifier = [1, 3, 132, 0, 10]
+        }
+
+        enum HashFunctions {
+            static let sha256: ASN1.ASN1ObjectIdentifier = [2, 16, 840, 1, 101, 3, 4, 2, 1]
+            static let sha384: ASN1.ASN1ObjectIdentifier = [2, 16, 840, 1, 101, 3, 4, 2, 2]
+            static let sha512: ASN1.ASN1ObjectIdentifier = [2, 16, 840, 1, 101, 3, 4, 2, 3]
+        }
+
+        enum AlgorithmIdentifier {
+            static let idEcPublicKey: ASN1.ASN1ObjectIdentifier = [1, 2, 840, 10045, 2, 1]
+        }
+
+        enum NameAttributes {
+            static let name: ASN1.ASN1ObjectIdentifier = [2, 5, 4, 41]
+            static let surname: ASN1.ASN1ObjectIdentifier = [2, 5, 4, 4]
+            static let givenName: ASN1.ASN1ObjectIdentifier = [2, 5, 4, 42]
+            static let initials: ASN1.ASN1ObjectIdentifier = [2, 5, 4, 43]
+            static let generationQualifier: ASN1.ASN1ObjectIdentifier = [2, 5, 4, 44]
+            static let commonName: ASN1.ASN1ObjectIdentifier = [2, 5, 4, 3]
+            static let localityName: ASN1.ASN1ObjectIdentifier = [2, 5, 4, 7]
+            static let stateOrProvinceName: ASN1.ASN1ObjectIdentifier = [2, 5, 4, 8]
+            static let organizationName: ASN1.ASN1ObjectIdentifier = [2, 5, 4, 10]
+            static let organizationalUnitName: ASN1.ASN1ObjectIdentifier = [2, 5, 4, 11]
+            static let title: ASN1.ASN1ObjectIdentifier = [2, 5, 4, 12]
+            static let dnQualifier: ASN1.ASN1ObjectIdentifier = [2, 5, 4, 46]
+            static let countryName: ASN1.ASN1ObjectIdentifier = [2, 5, 4, 6]
+            static let serialNumber: ASN1.ASN1ObjectIdentifier = [2, 5, 4, 5]
+            static let pseudonym: ASN1.ASN1ObjectIdentifier = [2, 5, 4, 65]
+            static let domainComponent: ASN1.ASN1ObjectIdentifier = [0, 9, 2342, 19200300, 100, 1, 25]
+            static let emailAddress: ASN1.ASN1ObjectIdentifier = [1, 2, 840, 113549, 1, 9, 1]
+        }
+    }
+
+    fileprivate extension ArraySlice where Element == UInt8 {
+        mutating func readOIDSubidentifier() throws -> UInt {
+            // In principle OID subidentifiers can be too large to fit into a UInt. We are choosing to not care about that
+            // because for us it shouldn't matter.
+            guard let subidentifierEndIndex = firstIndex(where: { $0 & 0x80 == 0x00 }) else {
+                throw CryptoKitASN1Error.invalidASN1Object
+            }
+
+            let oidSlice = self[startIndex...subidentifierEndIndex]
+            self = self[index(after: subidentifierEndIndex)...]
+
+            // We need to compact the bits. These are 7-bit integers, which is really awkward.
+            return try UInt(sevenBitBigEndianBytes: oidSlice)
+        }
+    }
+
+    fileprivate extension UInt {
+        init<Bytes: Collection>(sevenBitBigEndianBytes bytes: Bytes) throws where Bytes.Element == UInt8 {
+            // We need to know how many bytes we _need_ to store this "int".
+            guard ((bytes.count * 7) + 7) / 8 <= MemoryLayout<UInt>.size else {
+                throw CryptoKitASN1Error.invalidASN1Object
+            }
+
+            self = 0
+            let shiftSizes = stride(from: 0, to: bytes.count * 7, by: 7).reversed()
+
+            var index = bytes.startIndex
+            for shift in shiftSizes {
+                self |= UInt(bytes[index] & 0x7F) << shift
+                bytes.formIndex(after: &index)
+            }
+        }
+    }
+
+#endif // Linux or !SwiftPM

Sources/zkp/ASN1/ECDSASignature.swift

@@ -0,0 +1 @@
+../../../Submodules/swift-crypto/Sources/Crypto/ASN1/ECDSASignature.swift

Sources/zkp/ASN1/PEMDocument.swift

@@ -0,0 +1 @@
+../../../Submodules/swift-crypto/Sources/Crypto/ASN1/PEMDocument.swift

Sources/zkp/ASN1/PKCS8PrivateKey.swift

@@ -0,0 +1 @@
+../../../Submodules/swift-crypto/Sources/Crypto/ASN1/PKCS8PrivateKey.swift