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refactor: align realm claims with profiles
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Refactor realm claims to align with PSA token profile definitions and to
allow them to be potentially extended in an analogous way via CCA
profiles.

- Use psatoken.IClaimsBase to define realm.IClaims. This exposes
  operations common to all claims objects, namely marshalling and
  validation.
- Expose previously internal realm.validate() as realm.ValidateClaims().
  This will help with implementing profiles that do not embed the
  original claims structure.
- Expose individual claim field validators and rename them from
  isValidXXX (which implies a boolean return) to ValidateXXX. This will
  be useful if, e.g., client code wants to make sure a hash is a valid
  realm challenge without needing a claims structure.
- Reuse errors defined inside psatoken, rather then re-defining them for
  realm claims. Errors such as "syntax error" or "missing mandatory
  claims" are in effect part of the generic IClaimsBase interface (i.e.
  common to all profile-able claims objects).
- Do not use json tags inside error messages, as they may be different
  for profiles that implement their own claims without embedding
  existing ones.
- Some minor stylistic tidying (consistent spacing, etc).

Signed-off-by: Sergei Trofimov <[email protected]>
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@setrofim
setrofim committed Jul 3, 2024
1 parent 9849f1f commit 18b4708
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Showing 6 changed files with 99 additions and 127 deletions.
2 changes: 1 addition & 1 deletion evidence_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -448,7 +448,7 @@ func TestEvidence_SetClaims_invalid_realm(t *testing.T) {
err = incompleteRealmClaims.SetPubKeyHashAlgID("sha-256")
require.NoError(t, err)

expectedErr := "validation of cca-realm-claims failed: validating cca-realm-challenge claim: missing mandatory claim"
expectedErr := "validation of cca-realm-claims failed: validating realm challenge claim: missing mandatory claim"

var e Evidence

Expand Down
68 changes: 35 additions & 33 deletions realm/claims.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@ import (
"fmt"

"github.com/veraison/eat"
"github.com/veraison/psatoken"
)

type Claims struct {
Expand All @@ -21,7 +22,7 @@ type Claims struct {
// Setters

func (c *Claims) SetChallenge(v []byte) error {
if err := isValidChallenge(v); err != nil {
if err := ValidateChallenge(v); err != nil {
return err
}

Expand All @@ -35,7 +36,7 @@ func (c *Claims) SetChallenge(v []byte) error {
}

func (c *Claims) SetPersonalizationValue(v []byte) error {
if err := isValidPersonalizationValue(v); err != nil {
if err := ValidatePersonalizationValue(v); err != nil {
return err
}

Expand All @@ -44,7 +45,7 @@ func (c *Claims) SetPersonalizationValue(v []byte) error {
}

func (c *Claims) SetInitialMeasurement(v []byte) error {
if err := isValidRealmMeas(v); err != nil {
if err := ValidateRealmMeas(v); err != nil {
return err
}

Expand All @@ -53,7 +54,7 @@ func (c *Claims) SetInitialMeasurement(v []byte) error {
}

func (c *Claims) SetExtensibleMeasurements(v [][]byte) error {
if err := isValidExtensibleMeas(v); err != nil {
if err := ValidateExtensibleMeas(v); err != nil {
return err
}

Expand All @@ -62,7 +63,7 @@ func (c *Claims) SetExtensibleMeasurements(v [][]byte) error {
}

func (c *Claims) SetHashAlgID(v string) error {
if err := isValidHashAlgID(v); err != nil {
if err := ValidateHashAlgID(v); err != nil {
return err
}

Expand All @@ -71,7 +72,7 @@ func (c *Claims) SetHashAlgID(v string) error {
}

func (c *Claims) SetPubKey(v []byte) error {
if err := isValidRealmPubKey(v); err != nil {
if err := ValidateRealmPubKey(v); err != nil {
return err
}

Expand All @@ -81,7 +82,7 @@ func (c *Claims) SetPubKey(v []byte) error {

func (c *Claims) SetPubKeyHashAlgID(v string) error {
if v == "" {
return fmt.Errorf("invalid null string set for cca-realm-pubkey-hash-algo-id")
return fmt.Errorf("invalid null string set for realm pubkey hash alg ID")
}

c.PublicKeyHashAlgID = &v
Expand All @@ -91,65 +92,69 @@ func (c *Claims) SetPubKeyHashAlgID(v string) error {
// Getters
func (c Claims) GetChallenge() ([]byte, error) {
v := c.Challenge

if v == nil {
return nil, ErrMandatoryClaimMissing
return nil, psatoken.ErrMandatoryClaimMissing
}

l := v.Len()

if l != 1 {
return nil, fmt.Errorf("%w: got %d nonces, want 1", ErrWrongClaimSyntax, l)
return nil, fmt.Errorf("%w: got %d nonces, want 1", psatoken.ErrWrongSyntax, l)
}

n := v.GetI(0)
if err := isValidChallenge(n); err != nil {
if err := ValidateChallenge(n); err != nil {
return nil, err
}

return n, nil
}

func (c Claims) GetPersonalizationValue() ([]byte, error) {
v := c.PersonalizationValue

if v == nil {
return nil, ErrMandatoryClaimMissing
return nil, psatoken.ErrMandatoryClaimMissing
}
if err := isValidPersonalizationValue(*v); err != nil {

if err := ValidatePersonalizationValue(*v); err != nil {
return nil, err
}

return *v, nil
}

func (c Claims) GetInitialMeasurement() ([]byte, error) {

v := c.InitialMeasurement
if v == nil {
return nil, ErrMandatoryClaimMissing
return nil, psatoken.ErrMandatoryClaimMissing
}
if err := isValidRealmMeas(*v); err != nil {

if err := ValidateRealmMeas(*v); err != nil {
return nil, err
}

return *v, nil
}

func (c Claims) GetExtensibleMeasurements() ([][]byte, error) {
v := c.ExtensibleMeasurements
if v == nil {
return nil, ErrMandatoryClaimMissing
return nil, psatoken.ErrMandatoryClaimMissing
}
if err := isValidExtensibleMeas(*v); err != nil {

if err := ValidateExtensibleMeas(*v); err != nil {
return nil, err
}

return *v, nil
}

func (c Claims) GetHashAlgID() (string, error) {
v := c.HashAlgID
if v == nil {
return "", ErrMandatoryClaimMissing
return "", psatoken.ErrMandatoryClaimMissing
}
if err := isValidHashAlgID(*v); err != nil {
if err := ValidateHashAlgID(*v); err != nil {
return "", err
}
return *v, nil
Expand All @@ -159,10 +164,10 @@ func (c Claims) GetPubKey() ([]byte, error) {
v := c.PublicKey

if v == nil {
return nil, ErrMandatoryClaimMissing
return nil, psatoken.ErrMandatoryClaimMissing
}

if err := isValidRealmPubKey(*v); err != nil {
if err := ValidateRealmPubKey(*v); err != nil {
return nil, err
}

Expand All @@ -173,14 +178,15 @@ func (c Claims) GetPubKeyHashAlgID() (string, error) {
v := c.PublicKeyHashAlgID

if v == nil {
return "", ErrMandatoryClaimMissing
return "", psatoken.ErrMandatoryClaimMissing
}

return *v, nil
}

// Semantic validation
func (c Claims) Validate() error {
return validate(&c)
return ValidateClaims(&c)
}

// Codecs
Expand Down Expand Up @@ -227,31 +233,27 @@ func (c Claims) ToUnvalidatedCBOR() ([]byte, error) {
}

func (c *Claims) FromJSON(buf []byte) error {
err := c.FromUnvalidatedJSON(buf)
if err != nil {
if err := c.FromUnvalidatedJSON(buf); err != nil {
return err
}

err = c.Validate()
if err != nil {
if err := c.Validate(); err != nil {
return fmt.Errorf("validation of CCA realm claims failed: %w", err)
}

return nil
}

func (c *Claims) FromUnvalidatedJSON(buf []byte) error {
err := json.Unmarshal(buf, c)
if err != nil {
if err := json.Unmarshal(buf, c); err != nil {
return fmt.Errorf("JSON decoding of CCA realm claims failed: %w", err)
}

return nil
}

func (c Claims) ToJSON() ([]byte, error) {
err := c.Validate()
if err != nil {
if err := c.Validate(); err != nil {
return nil, fmt.Errorf("validation of CCA realm claims failed: %w", err)
}

Expand Down
28 changes: 14 additions & 14 deletions realm/claims_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -46,27 +46,27 @@ func Test_CcaRealmClaims_Set_nok(t *testing.T) {
c := NewClaims()

err := c.SetChallenge([]byte("123"))
expectedErr := "wrong syntax for claim: length 3 (cca-hash-type MUST be 64 bytes)"
expectedErr := "wrong syntax: length 3 (hash MUST be 64 bytes)"
assert.EqualError(t, err, expectedErr)

err = c.SetPersonalizationValue([]byte("personalizationVal"))
expectedErr = "wrong syntax for claim: length 18 (cca-personalization-value MUST be 64 bytes)"
expectedErr = "wrong syntax: length 18 (personalization value MUST be 64 bytes)"
assert.EqualError(t, err, expectedErr)

err = c.SetInitialMeasurement([]byte("random"))
expectedErr = "wrong syntax for claim: length 6 (cca-realm-measurement MUST be 32, 48 or 64 bytes)"
expectedErr = "wrong syntax: length 6 (realm measurement MUST be 32, 48 or 64 bytes)"
assert.EqualError(t, err, expectedErr)

err = c.SetExtensibleMeasurements([][]byte{})
expectedErr = "missing mandatory claim cca-realm-extended-measurements"
expectedErr = "missing mandatory claim realm extended measurements"
assert.EqualError(t, err, expectedErr)

err = c.SetHashAlgID("")
expectedErr = "wrong syntax for claim: empty string"
expectedErr = "wrong syntax: empty string"
assert.EqualError(t, err, expectedErr)

err = c.SetPubKey([]byte("not-a-valid-point"))
expectedErr = "wrong syntax for claim: length 17 (cca-realm-public-key MUST be 97 bytes)"
expectedErr = "wrong syntax: length 17 (realm public key MUST be 97 bytes)"
assert.EqualError(t, err, expectedErr)

err = c.SetPubKey([]byte{
Expand All @@ -80,19 +80,19 @@ func Test_CcaRealmClaims_Set_nok(t *testing.T) {
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff,
})
expectedErr = "wrong syntax for claim: checking raw public key coordinates are on curve P-384: failed to unmarshal elliptic curve point"
expectedErr = "wrong syntax: checking raw public key coordinates are on curve P-384: failed to unmarshal elliptic curve point"
assert.EqualError(t, err, expectedErr)

err = c.SetPubKeyHashAlgID("")
expectedErr = "invalid null string set for cca-realm-pubkey-hash-algo-id"
expectedErr = "invalid null string set for realm pubkey hash alg ID"
assert.EqualError(t, err, expectedErr)
}

func Test_CcaRealmClaims_ToCBOR_invalid(t *testing.T) {
c := NewClaims()

_, err := c.ToCBOR()
expectedErr := `validation of CCA realm claims failed: validating cca-realm-challenge claim: missing mandatory claim`
expectedErr := `validation of CCA realm claims failed: validating realm challenge claim: missing mandatory claim`
assert.EqualError(t, err, expectedErr)
}

Expand Down Expand Up @@ -160,36 +160,36 @@ func Test_CcaRealmClaims_FromCBOR_bad_input(t *testing.T) {
func Test_CcaRealmClaims_FromCBOR_missing_mandatory_claims(t *testing.T) {
buf := mustHexDecode(t, testEncodedCcaRealmClaimsMissingMandNonce)

expectedErr := "validation of CCA realm claims failed: validating cca-realm-challenge claim: missing mandatory claim"
expectedErr := "validation of CCA realm claims failed: validating realm challenge claim: missing mandatory claim"

var c Claims
err := c.FromCBOR(buf)
assert.EqualError(t, err, expectedErr)

buf = mustHexDecode(t, testEncodedCcaClaimsMissingMandInitialMeas)

expectedErr = "validation of CCA realm claims failed: validating cca-realm-initial-measurements claim: missing mandatory claim"
expectedErr = "validation of CCA realm claims failed: validating realm initial measurements claim: missing mandatory claim"
c = Claims{}
err = c.FromCBOR(buf)
assert.EqualError(t, err, expectedErr)

buf = mustHexDecode(t, testEncodedCcaClaimsMissingMandHashAlgID)

expectedErr = "validation of CCA realm claims failed: validating cca-realm-hash-alg-id claim: missing mandatory claim"
expectedErr = "validation of CCA realm claims failed: validating realm hash alg ID claim: missing mandatory claim"
c = Claims{}
err = c.FromCBOR(buf)
assert.EqualError(t, err, expectedErr)

buf = mustHexDecode(t, testEncodedCcaClaimsMissingMandPubKey)

expectedErr = "validation of CCA realm claims failed: validating cca-realm-public-key claim: missing mandatory claim"
expectedErr = "validation of CCA realm claims failed: validating realm public key claim: missing mandatory claim"
c = Claims{}
err = c.FromCBOR(buf)
assert.EqualError(t, err, expectedErr)

buf = mustHexDecode(t, testEncodedCcaClaimsMissingMandExtendedMeas)

expectedErr = "validation of CCA realm claims failed: validating cca-realm-extended-measurements claim: missing mandatory claim"
expectedErr = "validation of CCA realm claims failed: validating realm extended measurements claim: missing mandatory claim"
c = Claims{}
err = c.FromCBOR(buf)
assert.EqualError(t, err, expectedErr)
Expand Down
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