feat: add algo hash list for digest calc in config

Introduce cobra/config flag that allows for slice of string's indicating
hash algorithms to be used for digest calculation. Uses
go-witness.attestation.WithHashes to add the slice to attestation run
options. Will error if can't parse hash from its string value.

Add test for testing acceptable/unacceptable hash algorithms accepted.

Refs: #73

cmd/run.go

@@ -16,6 +16,7 @@ package cmd
 
 import (
 	"context"
+	"crypto"
 	"encoding/json"
 	"fmt"
 
@@ -102,12 +103,21 @@ func runRun(ctx context.Context, ro options.RunOptions, args []string, signers .
 		}
 	}
 
+	var roHashes []crypto.Hash
+	for _, hashStr := range ro.Hashes {
+		hash, err := cryptoutil.HashFromString(hashStr)
+		if err != nil {
+			return fmt.Errorf("failed to parse hash: %w", err)
+		}
+		roHashes = append(roHashes, hash)
+	}
+
 	defer out.Close()
 	result, err := witness.Run(
 		ro.StepName,
 		signers[0],
 		witness.RunWithAttestors(attestors),
-		witness.RunWithAttestationOpts(attestation.WithWorkingDir(ro.WorkingDir)),
+		witness.RunWithAttestationOpts(attestation.WithWorkingDir(ro.WorkingDir), attestation.WithHashes(roHashes)),
 		witness.RunWithTimestampers(timestampers...),
 	)
 

cmd/run_test.go

@@ -116,3 +116,58 @@ func Test_runRunRSACA(t *testing.T) {
 	require.NoError(t, err)
 	assert.Equal(t, b, env.Signatures[0].Certificate)
 }
+
+func TestRunHashesOptions(t *testing.T) {
+	tests := []struct {
+		name         string
+		hashesOption []string
+		expectErr    bool
+	}{
+		{
+			name:         "Valid RSA key pair",
+			hashesOption: []string{"sha256"},
+			expectErr:    false,
+		},
+		{
+			name:         "Invalid hashes option",
+			hashesOption: []string{"invalidHash"},
+			expectErr:    true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			privatekey, err := rsa.GenerateKey(rand.Reader, keybits)
+			require.NoError(t, err)
+			signer := cryptoutil.NewRSASigner(privatekey, crypto.SHA256)
+
+			workingDir := t.TempDir()
+			attestationPath := filepath.Join(workingDir, "outfile.txt")
+			runOptions := options.RunOptions{
+				WorkingDir:   workingDir,
+				Attestations: []string{},
+				Hashes:       tt.hashesOption,
+				OutFilePath:  attestationPath,
+				StepName:     "teststep",
+				Tracing:      false,
+			}
+
+			args := []string{
+				"bash",
+				"-c",
+				"echo 'test' > test.txt",
+			}
+
+			err = runRun(context.Background(), runOptions, args, signer)
+			if tt.expectErr {
+				require.Error(t, err)
+			} else {
+				require.NoError(t, err)
+				attestationBytes, err := os.ReadFile(attestationPath)
+				require.NoError(t, err)
+				env := dsse.Envelope{}
+				require.NoError(t, json.Unmarshal(attestationBytes, &env))
+			}
+		})
+	}
+}

options/run.go

@@ -25,6 +25,7 @@ type RunOptions struct {
 	ArchivistaOptions  ArchivistaOptions
 	WorkingDir         string
 	Attestations       []string
+	Hashes             []string
 	OutFilePath        string
 	StepName           string
 	Tracing            bool
@@ -37,6 +38,7 @@ func (ro *RunOptions) AddFlags(cmd *cobra.Command) {
 	ro.ArchivistaOptions.AddFlags(cmd)
 	cmd.Flags().StringVarP(&ro.WorkingDir, "workingdir", "d", "", "Directory from which commands will run")
 	cmd.Flags().StringSliceVarP(&ro.Attestations, "attestations", "a", []string{"environment", "git"}, "Attestations to record")
+	cmd.Flags().StringSliceVar(&ro.Hashes, "hashes", []string{"sha256"}, "Hashes selected for digest calculation. Defaults to SHA256")
 	cmd.Flags().StringVarP(&ro.OutFilePath, "outfile", "o", "", "File to which to write signed data.  Defaults to stdout")
 	cmd.Flags().StringVarP(&ro.StepName, "step", "s", "", "Name of the step being run")
 	cmd.Flags().BoolVar(&ro.Tracing, "trace", false, "Enable tracing for the command")