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Changing minimum certificate rotation period and backdating to 1h #1243

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Aug 1, 2016
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Changing minimum certificate rotation period and backdating to 1h #1243

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12 changes: 5 additions & 7 deletions ca/certificates.go
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Original file line number Diff line number Diff line change
Expand Up @@ -57,19 +57,17 @@ const (
RootCAExpiration = "630720000s"
// DefaultNodeCertExpiration represents the default expiration for node certificates (3 months)
DefaultNodeCertExpiration = 2160 * time.Hour
// CertBackdate represents the amount of time each certificate is backdated to try to avoid
// clock drift issues.
CertBackdate = -1 * time.Hour
// CertLowerRotationRange represents the minimum fraction of time that we will wait when randomly
// choosing our next certificate rotation
CertLowerRotationRange = 0.5
// CertUpperRotationRange represents the maximum fraction of time that we will wait when randomly
// choosing our next certificate rotation
CertUpperRotationRange = 0.8
// MinNodeCertExpiration represents the minimum expiration for node certificates (25 + 5 minutes)
// X - 5 > CertUpperRotationRange * X <=> X < 5/(1 - CertUpperRotationRange)
// Since we're issuing certificates 5 minutes in the past to get around clock drifts, and
// we're selecting a random rotation distribution range from CertLowerRotationRange to
// CertUpperRotationRange, we need to ensure that we don't accept an expiration time that will
// make a node able to randomly choose the next rotation after the expiration of the certificate.
MinNodeCertExpiration = 30 * time.Minute
// MinNodeCertExpiration represents the minimum expiration for node certificates
MinNodeCertExpiration = 1 * time.Hour
)

// ErrNoLocalRootCA is an error type used to indicate that the local root CA
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8 changes: 4 additions & 4 deletions ca/certificates_test.go
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Expand Up @@ -534,12 +534,12 @@ func TestNewRootCANonDefaultExpiry(t *testing.T) {
parsedCerts, err := helpers.ParseCertificatesPEM(cert)
assert.NoError(t, err)
assert.Len(t, parsedCerts, 2)
assert.True(t, time.Now().Add(time.Minute*50).Before(parsedCerts[0].NotAfter))
assert.True(t, time.Now().Add(time.Hour).After(parsedCerts[0].NotAfter))
assert.True(t, time.Now().Add(time.Minute*59).Before(parsedCerts[0].NotAfter))
assert.True(t, time.Now().Add(time.Hour).Add(time.Minute).After(parsedCerts[0].NotAfter))

// Sign the same CSR again, this time with a 29 Minute expiration RootCA (under the 30 minute minimum).
// Sign the same CSR again, this time with a 59 Minute expiration RootCA (under the 60 minute minimum).
// This should use the default of 3 months
newRootCA, err = ca.NewRootCA(rootCA.Cert, rootCA.Key, 29*time.Minute)
newRootCA, err = ca.NewRootCA(rootCA.Cert, rootCA.Key, 59*time.Minute)
assert.NoError(t, err)

cert, err = newRootCA.ParseValidateAndSignCSR(csr, "CN", ca.ManagerRole, "ORG")
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10 changes: 8 additions & 2 deletions ca/config.go
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Expand Up @@ -124,10 +124,16 @@ func SigningPolicy(certExpiry time.Duration) *cfconfig.Signing {
certExpiry = DefaultNodeCertExpiration
}

now := time.Now()
notBefore := now.Round(time.Minute).Add(CertBackdate).UTC()
notAfter := now.Round(time.Minute).Add(certExpiry).UTC()

return &cfconfig.Signing{
Default: &cfconfig.SigningProfile{
Usage: []string{"signing", "key encipherment", "server auth", "client auth"},
Expiry: certExpiry,
Usage: []string{"signing", "key encipherment", "server auth", "client auth"},
Expiry: certExpiry,
NotBefore: notBefore,
NotAfter: notAfter,
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Probably a dumb TLS question, but is it correct to specify both NotBefore / NotAfter and also Expiry? Does cfssl use both of them?

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@diogomonica diogomonica Jul 26, 2016 •
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CFSSL is silly and doesn't seem to allow me to not specify Expiry. Tells me this is an invalid profile. Didn't dig super far into it though, I might be missing something obvious.

In TLS there is not concept of Expiry, the only two things that matter are notBefore and notAfter.

This is the code that fills in the notBefore and notAfter: https://github.com/cloudflare/cfssl/blob/f8a8adaa9d48141125b78c23553a174845661522/signer/signer.go#L280

// Only trust the key components from the CSR. Everything else should
// come directly from API call params.
CSRWhitelist: &cfconfig.CSRWhitelist{
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