feat: add sha256 checksum extension (#45)

awslabs · Sep 29, 2021 · fcedf0c · fcedf0c
1 parent 737c445
commit fcedf0c
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Showing 2 changed files with 33 additions and 0 deletions.
diff --git a/Source/AwsCommonRuntimeKit/Utilities.swift b/Source/AwsCommonRuntimeKit/Utilities.swift
@@ -41,6 +41,19 @@ extension String {
         let byteCursor = aws_byte_cursor_from_buf(output)
         return byteCursor.toData().base64EncodedString()
     }
+
+    public func base64EncodedSha256(allocator: Allocator = defaultAllocator, truncate: Int = 0) -> String {
+        let input: UnsafePointer<aws_byte_cursor> = fromPointer(ptr: self.awsByteCursor)
+        let emptyBuffer: UInt8 = 0
+        let bufferPtr: UnsafeMutablePointer<UInt8> = fromPointer(ptr: emptyBuffer)
+        let buffer = aws_byte_buf(len: 0, buffer: bufferPtr, capacity: Int(AWS_SHA256_LEN), allocator: allocator.rawValue)
+        let output: UnsafeMutablePointer<aws_byte_buf> = fromPointer(ptr: buffer)
+
+        aws_sha256_compute(allocator.rawValue, input, output, truncate)
+
+        let byteCursor = aws_byte_cursor_from_buf(output)
+        return byteCursor.toData().base64EncodedString()
+    }
 }
 
 public extension Int32 {

diff --git a/Test/AwsCommonRuntimeKitTests/crt/UtilityTests.swift b/Test/AwsCommonRuntimeKitTests/crt/UtilityTests.swift
@@ -22,5 +22,25 @@ class UtilityTests: XCTestCase {
 
         XCTAssertEqual(md5, "iB0/3YSo7maijL0IGOgA9g==")
     }
+
+    func testSha256() throws {
+        let hello = "Hello"
+        let sha256 = hello.base64EncodedSha256()
+        XCTAssertEqual(sha256, "GF+NsyJx/iX1Yab8k4suJkMG7DBO2lGAB9F2SCY4GWk=")
+    }
+
+    func testSha256_EmptyString() throws {
+        let empty = ""
+        let sha256 = empty.base64EncodedSha256()
+        XCTAssertEqual(sha256, "47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU=")
+    }
+
+    func testSha256_payload() throws {
+        let payload = "{\"foo\":\"base64 encoded sha256 checksum\"}"
+
+        let sha256 = payload.base64EncodedSha256()
+
+        XCTAssertEqual(sha256, "lBSnDP4sj/yN8eIVOJlv+vC56hw+7JtN0132GiMQXRg=")
+    }
 }