HP 635n Practical IPsec Deployment for Printing and Imaging Devices - Page 101

Symmetric Cryptography

Get HP 635n - JetDirect IPv6/IPsec Print Server PDF manuals and user guides
UPC - 882780301016
View all HP 635n manuals
Add to My Manuals
Save this manual to your list of manuals

Page 101 highlights

There is a red X on the certificate, indicative of a security problem. In addition, there is a very specific error message: "This certificate cannot be verified up to a trusted certification authority." Here we see that the "Issued By" is entitled "RootCA". What the message is trying to say is that "RootCA", who issued the certificate "635n", is not trusted. A useful analogy is to think of the certificate issuer like the California Department of Motor Vehicles (DMV). Each state in the United States has a DMV run by the state's government. The DMV issues driver's licenses which grant the privilege to drive in a given state. A person that goes to the DMV to get a driver's license must pass a series of tests that helps the DMV determine if they are fit to drive on the state's roads. The state's Highway Patrol, a group which enforces the rules of the road, recognizes the validity of the DMV to issue driver's licenses. Therefore, if one violates one of the rules of the road and is pulled over by a Highway Patrol officer, showing a driver's license issued by the DMV is a requirement. The Highway Patrol will not recognize a driver's license issued by an institution other than the DMV as being valid. In short, the DMV is a trusted third party that issues "certificates" (driver's licenses) to individuals. These "certificates", issued by the DMV, are trusted by the Highway Patrol. The Security Alert dialog is troubling because it is indicative of a trust problem. In the terms of our analogy, it would be like a driver, who has been pulled over by the Highway Patrol, handing the officer a driver's license that the driver's mother wrote for him indicating that her son had been granted the privilege to drive in the state. While a note from mom may be trusted by her sister, it isn't trusted by the Highway Patrol. In essence, a digital certificate, one used by computers, binds an identity to a key and needs to be issued by a trusted third party. What is a key? A key is a secret that is used in cryptographic algorithms. There are public keys and private keys used for asymmetric cryptography and symmetric keys used for symmetric cryptography. Let's look at symmetric cryptography first. User Unencrypted Message Encryption Performed Message Delivery Decryption Performed User Unencrypted Message Figure 46 - Symmetric Cryptography 101

  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
  • 9
  • 10
  • 11
  • 12
  • 13
  • 14
  • 15
  • 16
  • 17
  • 18
  • 19
  • 20
  • 21
  • 22
  • 23
  • 24
  • 25
  • 26
  • 27
  • 28
  • 29
  • 30
  • 31
  • 32
  • 33
  • 34
  • 35
  • 36
  • 37
  • 38
  • 39
  • 40
  • 41
  • 42
  • 43
  • 44
  • 45
  • 46
  • 47
  • 48
  • 49
  • 50
  • 51
  • 52
  • 53
  • 54
  • 55
  • 56
  • 57
  • 58
  • 59
  • 60
  • 61
  • 62
  • 63
  • 64
  • 65
  • 66
  • 67
  • 68
  • 69
  • 70
  • 71
  • 72
  • 73
  • 74
  • 75
  • 76
  • 77
  • 78
  • 79
  • 80
  • 81
  • 82
  • 83
  • 84
  • 85
  • 86
  • 87
  • 88
  • 89
  • 90
  • 91
  • 92
  • 93
  • 94
  • 95
  • 96
  • 97
  • 98
  • 99
  • 100
  • 101
  • 102
  • 103
  • 104
  • 105
  • 106
  • 107
  • 108
  • 109
  • 110
  • 111
  • 112
  • 113
  • 114
  • 115
  • 116
  • 117
  • 118
  • 119
  • 120
  • 121
  • 122
  • 123
  • 124
  • 125
  • 126
  • 127
  • 128
  • 129
  • 130
  • 131
  • 132
  • 133
  • 134
  • 135
  • 136
  • 137
  • 138
  • 139
  • 140
  • 141
  • 142
  • 143
  • 144
  • 145
  • 146
  • 147
  • 148
  • 149
  • 150
  • 151
  • 152
  • 153
  • 154
  • 155
  • 156
  • 157
  • 158
  • 159
  • 160
  • 161
  • 162
  • 163
  • 164
  • 165
  • 166
  • 167
  • 168
  • 169
  • 170
  • 171
  • 172
  • 173
  • 174
  • 175
  • 176
  • 177
  • 178
  • 179
  • 180
  • 181
  • 182
  • 183
  • 184
  • 185
  • 186
  • 187
  • 188
  • 189
  • 190
  • 191
  • 192
  • 193
101
There is a red X on the certificate, indicative of a security problem.
In addition, there is a very
specific error message: “This certificate cannot be verified up to a trusted certification authority.”
Here we see that the “Issued By” is entitled “RootCA”.
What the message is trying to say is that
“RootCA”, who issued the certificate “635n”, is not trusted.
A useful analogy is to think of the certificate issuer like the California Department of Motor Vehicles
(DMV).
Each state in the United States has a DMV run by the state’s government.
The DMV issues
driver’s licenses which grant the privilege to drive in a given state.
A person that goes to the DMV to
get a driver’s license must pass a series of tests that helps the DMV determine if they are fit to drive on
the state’s roads. The state’s Highway Patrol, a group which enforces the rules of the road,
recognizes the validity of the DMV to issue driver’s licenses.
Therefore, if one violates one of the rules
of the road and is pulled over by a Highway Patrol officer, showing a driver’s license issued by the
DMV is a requirement.
The Highway Patrol will not recognize a driver’s license issued by an
institution other than the DMV as being valid.
In short, the DMV is a trusted third party that issues
“certificates” (driver’s licenses) to individuals.
These “certificates”, issued by the DMV, are trusted by
the Highway Patrol.
The Security Alert dialog is troubling because it is indicative of a trust problem.
In the terms of our
analogy, it would be like a driver, who has been pulled over by the Highway Patrol, handing the
officer a driver’s license that the driver’s mother wrote for him indicating that her son had been
granted the privilege to drive in the state.
While a note from mom may be trusted by her sister, it isn’t
trusted by the Highway Patrol.
In essence, a digital certificate, one used by computers, binds an identity to a key and needs to be
issued by a trusted third party.
What is a key?
A key is a secret that is used in cryptographic
algorithms.
There are public keys and private keys used for asymmetric cryptography and symmetric
keys used for symmetric cryptography.
Let’s look at symmetric cryptography first.
Message Delivery
User
Encryption Performed
User
Decryption Performed
Unencrypted Message
Unencrypted Message
Figure 46 – Symmetric Cryptography